Even Mutilate I think is better done statistically than via simulation. I've actually worked out about 75% of the behavior by hand before; it's just never been worth taking the time to include that information in a spreadsheet.

In terms of writing a computer program to do this statistically: I'd be willing to write the actual computation package for it myself, but there's a lot of code around that that would need to be written as well. I mean, here's an overview of what would be involved in the ideal rogue calculator:

1) UI for entering gear and talents. Ideally this would also include an Armory fetch so you can point it at your Armory Profile and it automatically grabs your gear and spec. Would also have a full talent calculator page where you can adjust your spec, and a way of changing out gear (probably something akin to the old CTProfiles).

2) Total up all stats, procs, etc. etc. from gear, and pass that information into the damage calculator. Damage calculator chews on it a bit and spits out a damage estimate.

3) For each stat (or maybe each piece of gear, or perhaps both) you rerun the damage calculation for your gear with one additional point in that stat. You use this to score each stat; then, you run these scores against an item database to get a rough score for each piece of gear to build a list of "these pieces of gear are good".

4) Then, for each of those pieces of gear, you run the damage calculator again, to get the exact upgrade from using that piece of gear versus what you're wearing. You then use this to build a list of "if you swap out this one piece of gear, this is the benefit you'd expect to get.

5) You display a list for each slot consisting of "this is how good the item is in an abstract sense, and this is how good it would be for you" - i.e., if you're hit-capped, items with high hit would still show as "good" but not an upgrade for you.

6) Ideally, you also add zone filters and the like to restrict the list of gear it returns, and other such nice features. Note also that socketing adds a lot of complexity to the above.

So, you'll note that this contains a lot of sorting and UI-type work above and beyond the actual calculator; the damage calculator itself, while perhaps the more technically sophisticated piece that requires the most knowledge, is probably less than half of the actual code that needs to be written. The rest doesn't require any particular patience or even that much coding sophistication; just lots and lots of time and effort.

Note also that you can get away without a lot of the fancy UI tweaks and gismos, but you fundamentally do need:

a) A way of entering your gear
b) A way of entering your spec
and
c) A way of displaying a damage number and an upgrades list

even if you do nothing else - and that's still work.

So, yeah. You probably only need one programmer with actual understanding of the mechanics and statistics that go into the DPS calculations - and I'd be willing to be that one - but you'd still need some people to invest the time and effort to write all the rest as well.

Aldriana drop Tornhoof a pm, he currently is already working on a simulator and gear optimizer using some "genetic algorithm". I have no idea what that is, but it's nerdy enough for me.

[Math models] Request for assistance

"Better" is highly subjective. T5 4pc won't allow you to do 2s/5r the way T4 2pc does, but it is a very potent set bonus nonetheless, completely worth running a longer cycle like 5s/5r.

It is basically always more important to keep 100% SnD uptime than anything else. If you worked hard enough coming up with a wierd gear combination you might be able to find one where that isn't true, but it's a good rule of thumb. SnD generates more damage per unit time than Rupture does.

Generally not, actually, for two reasons:

1) By the time you're at 2/5 T6, you generally have T5-equivalent gear in almost all slots; and for most people, dropping two pieces of T5 for T4 is a larger damage loss than what you gain from T4 2/5.

2) As your gear level increases into the T6 range, the value of T4 2/5 decreases.

Now, if you're in a situation where, for instance, you've picked up T6 gloves and helm but are still using T4 shoulders since Void Reaver hasn't cooperated, you could imagine using T4 legs for the set bonus until you got a shoulder upgrade. But this is pretty rare, on the whole; as a general rule of thumb, using 2/5 T4 until 4/5 T5 and then abandoning it forever is the way to go.

I'd also encourage you to work through the Rogue Gear Spreadsheet a bit; for whatever gear you're currently wearing, it will tell you the exact upgrade provided by each piece of gear and each set bonus, allowing you to work this out exactly for your particular case.