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!

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?

Ah thats cool..
I already have double crusader so I'll definately keep it!
The double proc is deadly in pvp too, when it happens

~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.

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

Misses from dual wielding, I think. Partly compensated by haste effects, but not enough to bridge the miss rate.

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).