I'm a DW fury warrior. Currently both my weapons are crusader enchanted, but I'm not sure on the Offhand proc-rate.
Would it be better to get +15 STR on average (for OH) over crusader?
I still like the occasional heals and big numbers dual crusader gives though!

If I remember Correctly the offhand proc rate averages out to about 22 str, and double crusader procs rule.

On my spreadsheet, offhand averages out to about 22 str. The great thing is that there is very little that influences offhand proc rate(haste), so I can say with a good amount of confidence that the number is correct. 7 more str worth the extra price? Usually is for me, especially since a lot of my offhand weapons were originally mainhand weapons.

I've got dual crusader, as a rogue, and I think I prefer it. +15 agi is technically better for offhand, but as the above poster said, my offhands tend to have been my MH weapon before. Additionally, the difference isn't so big that I personally feel the extra healing is worth it. For soloing it's great, and while I can't quantify the amount exactly, I'm sure the extra healing has saved my life more then a few times. A dead rogue does 0 dps.

Is the procrate on crusader so low that +15 agi is really better?

For a Rogue 15 agility > ~22 str (it may be a little higher with slice n' dice), however, that extra healing Crusader gets is always nice to have.

That said, I feel the difference isn't enought that I would reenchant (if the weapon already had Crusader).

~22 ap vs 15 ap and .5% crit, so yes. As deathwing said, offhand proc rate is much lower.

But, occasionally you get double procs, which are fun. Occasionally, I can manage to time Adrenaline rush with double procs and crank out some extra DPS. It's rare, but it happens sometimes. +15agi on offhand is definitely higher dps though. I'm not arguing against it, but it's not something like a 10dps difference, so I personally feel the extra healing is worth it, and I don't want to renchant my offhand weapon, which tends to get sharded quicker then whatever my MH is. A new weapon tends to go Mh, then pushed to my OH.

Plugging several sets of gear into chalon's spreadsheet shows the difference in dps to be minimal, with +15 agi coming out as superior for lesser sets of gear, and crusader as better for more well-geared rogues, unbuffed. Buffed, +15 agi is on top always, but only by small fractions. His modeling of the proc seems to be 24.5 strength instead of 22 as you have modeled, so that may account for something.

I do like double procs though, I guess that's something you just can't model well.

The healing is nice too. :P Its definately worth the money.

His is a bit higher because you can pretty much guaruntee 100% haste for rogues...warriors will never get 100% haste.

What % of the time do you assume warriors have flurry up to get ~22 str?

If it procs in offhand at 1ppm as with in main hand, wouldn't that mean it's up 15 in 60 seconds and average out to 25 str? What am I missing :S

Judging from this, the best setup for Rogue would be Crusader on Mainhand and +15 Agility on offhand? Or is, mathemetically, +15 Agility better than Crusader on Main Hand as well?

Crusader main/agi off is generally the best combo for rogues, with current gear levels (the crit compenent from the agi enchant means that theoretically it could scale to perform better than crusader for MH, but even with the best gear currently in-game, crusader still comes out on top for now - and by the time there's better gear available, we'll be looking at expansion weapons and enchants anyway). There's not a lot in it, though, the differences between them are miniscule (and if you're daggers, +5 is another very competitive option, which some people prefer over crusader because it's consistent, rather than proc-based, and it has the added benefit of being relatively cheap).

No, the miss rate has nothing to do with it. Basically, for any swing to be flurried, you need a crit within the timespan of the previous 3 swings. Unless you have 100% crit rate, there's always a chance that you won't get that crit, hence no 100% haste. Also, flurry is on steep diminishing returns, higher crit rates give you less and less flurry increase.

Lastly, the way enchants like Crusader works(as in, it can be on a variety of weapons), they are set at 1PPM, but that's 1PPM based on unhasted auto-attack. The proc rate goes up once you start throwing in haste and yellow attacks. So, slower weapons gets high proc rates in this system.

How does increase in crit give diminishing returns for flurry?

The higher your crit, the more flurry procs that are wasted by overlap. With 1% crit, each crit will usually haste the next three attacks. With 99% crit, each crit will usually only haste the next attac (as that attack will be a crit, wasting two swings from the first crit).

It's worth noting that simply using BT and WW every time they are up is huge for improving flurry uptime, and generating crits is Spamstringing's real reason for existance.

Horde have a huge advantage using spamstring as they can proc Windfury off a hamstring (thats what I hear anyway).
I usually don't bother with hamstring, I change between battle/fury alot for OP/WW so my rage stays down (even though thats not ideal)

Nothing wrong with that. There's still a lot of variation in how you manage your rage and damage based on the amount of rage you generate and how much of an aggro threshold you can push. Taking advantage of Improved OP can add a decent amount of flurry uptime, but if you don't have IOp it's usually not worth switching (unless you are using a 2Her, but if that's the case why would you not have IOp?). If you sit in Berserker stance most of the time pushing your aggro with just BT/WW and need to get a flurry going hitting Hamstring is still the most effective way to do it if BT and WW are down. Horde-side spamstringing is mighty effective with a 2H weapon, but when DWing the point of doing it remains the same: get a crit and feed your flurry.

Okay so even if there are huge diminishing returns with a higher crit rate, your DPS/Damage Output would still be significantly higher wouldn't it? As inefficent as it might be to not use all your flurry charge, the ability to keep flurry up would be more important correct?

+Crit scales somewhat poorly in regards to flurry uptime, but it's still a good way to improve overall DPS and it scales better in DPS terms than your 9th point of +hit. The only thing that really scales at a linear level is AP.