There is one other reason you may not want to take DP over something like SW or HA.
I used to run DP with mediocre gear that provided maybe 20% haste without raid buffs. With haste being one of our most beneficial stats, i found the following (and you will most likely encounter the same) to happen far too often:

You reach 5HP and use TV. You proc DP. During your DP proc, you use what abilities are not on cooldown to reach 5HP again until they are all on CD, then you may spend your DP to prevent downtime on abilities. DP proc's again. You repeat the above process, and at this point you've most likely reached 5HP and still have maybe a CS or an AoW Exo available. At this point you have no choice but to burn DP then 3HP before you can use your CS/Exo/J/HoW, otherwise its a wasted HP generation at cap. If the game is feeling exceptionally sinister, it'll proc your DP again while you are trying to burn it off.

While the idea of chain-proc DP might sound appealing, those CS/J/Exo/HoW not spend are basically wasted opportunities.
I have found running HA has provided me with the following situation instead:

(Extract from Exemplar's CS vs J table)

GCD	Usage	Conflict?
1	CS	Yes
2	J	No
3	Something	No
4	CS	No
5	Something	No
6	J	No
7	CS	No
8	Something	No

I generally fill "something" with TV while HA is up. as HA is on a 2 min CD with AW on a 3 min CD, the situation of having HoW to compete with a position in that order only comes up during the first use of cooldowns then doesnt come back until 2 HA's later (unless you wanted to wait an additional minute on HA for AW to come off Cd, which is not recommended)
This is also a good reason to pick SW once you have your 4set. Odds are you've gotten some other shiny stuff along the way and your haste is getting very high. with AW being reduced to 1min55sec CD (basically, 2 mins) it means EVERY time you use AW with HA, you have to find a place for HoW amongs spamming TV every second skill with CS on a massively reduced CD (especially if you are still running wok trinket and use it accordingly) and AoW procs.

Cal me a heretic, but sometimes too much haste can feel like a burden during burst phases

That's extra super information. And yeah I totally feel the haste problem when using HA, because its usually used during Timewarp/Bloodlust and then it seems like I'm wasting a TON of HoWs...and that's just with a 486 ilvl, I can't even imagine how much worse it's going to get as I get upgrades.

I see no mention on haste breakpoints here, as it seems like haste only gets better with more of it, but will there be a point of haste wihere we should probably put more into mastery or crit? As we simply cannot utilize all the "procs" and holy power generation.

You will never notice it get better or worse acquiring more haste, because haste also lowers the GCD. For example, if haste DIDN'T lower the GCD, and it sat at a uniform 1.5 second, eventually too much haste would go wasted by the fact so much stuff was coming off cooldown as a result of GCD delay. for ret paladins, the game is essentially put into fast-forward the more haste we get.
I believe it was mentioned earlier, but haste actually ends up more valuable the better your gear gets (prior to this strength is highest priority, and the sweetspot in which this changes is not set in stone and heavily based on your own gear setup and playstyle. If you want to know when this changes for certain, I would recommend trying Simcraft) so keep pushing for more haste as your gear improves.

The availability of HoW during HA is unfortunately just a part of life for ret paladins pre-4set. Keep grinding LFR to get those last pieces then change over to SW. I dont have my 4set yet so I can only reiterate what more experienced (and lucky) rets have said, but I believe CD/burst rotation becomes much more efficient with this adjustment.

As for "haste breakpoints" (also known as Soft Caps) these normally refer to the amount of haste required to achieve an extra tick on DoTs, and is something mostly relevant to warlocks, boomkins, spriests and fire mages. With the way Censure operates we dont need to push for more ticks as we have a 100% uptime on it, it will just tick more often for the 100% duration we have.

Thanks! I really wanted to try SimCraft, but I cannot for the love of god get it to import my character. I then tried CharDev which does not support my Darkmoon trinket, nor does it support upgrades.

Any ideas?

Ah, that would explain it. Could you explain where and how to correct it a bit more in-depth? I've literally NEVER used simcraft and I cannot find the action lists or understand what SVN is

Thanks!

In the tab that SimCraft generates immediately after import is the actionlist. That line is near the bottom of the lines detailing actions, above the lines detailing gear. Just delete the s.

I don't use the GUI anymore or I'd post a screenshot showing you.

Sorry mate,

Nothing comes (apart from what I posted above). When I use it on my Druid, it completely shows me what you are trying to say, but with the paladin it straight up refuses up front.

Which is another excellent reason to build your own SimC from the SVN releases so you have constantly up to date releases with bugfixes quickly.

Until you reach 21259.5 haste rating, at which point the GCD cannot be lowered any further.

There's a new version of SimC out with the paladin stuff fixed. 510-3.

Thats a lot of haste! i believe i only have about 6-7k haste in my mix of LFR/VP gear (logged out in my pvp gear so cant be certain, D'oh!). reaching that amount of haste is probably something only Heroic gear could achieve, yes?
What attack speed percentage does 21259.5 provide? (so i can take into account attack speed raid buff and Heroism)

Would this be considered the hard cap for ret haste rating? (even though additional haste above this figure would continue to benefit white swings and ability CD's) if so it should be added to the first post. Can this be added?

SW itself doesnt provide any increased benefit to Judgement over CS through its mechanics, however AW allowing the use of HoW could be the reason you would consider changing your rotation.
I have found during full burst with HA my attack order becomes:

GCD	Usage	Conflict?
1	J	Yes
2	TV	No
3	HoW	No
4	TV	No
5	J	No
6	TV	No
7	HoW	No
8	Tv	No

There is about a half second delay in waiting for HoW to come off CD each time, but i am pretty confident waiting .5 of a second for HoW over CS is worth it. The only exception I make in this rotation is AoW/Exo replacing J when its available.
If you are not specced into SW, CS is still more valuable than J for the purpose of its shorter CD. This allows CS to pop up more often during rotation blindspots allowing for a more consistent flow of HP. Having HoW on a 50% reduced CD does assist the situation, but there are still circumstances were you will end up with blindspots in your rotation if you put J before CS

Exemplar's post in This Thread explains it in more detail.