Jason, I realize you are a little biased, but that isnt 100% true. I'm almost positive that you are right, each of the street disks are the same. However you can go with a sprung hub pucked disk and it will hold considerably more power. I'm pretty sure the ACT "Xtreme" is the 2600, and the street disk on that holds 400 ft lbs compared to the sprung 6 puck disk that holds 513 ft lbs. Hell, even the ACT "Heavy Duty" (pretty sure this is the 2100) with the sprung 6 puck holds 412 ft lbs. The pressure increase on the 2100 is supposed to be 27% and the 2600 is supposedly 48%.
In my own opinion, if you are having trouble with anything equivalent to or less than a 2600 then you need to take your ass to the gym once in a while. I've been doing quite a bit of city driving on mine and yes its noticable, but its no where near wearing my leg out, even on a 45 minute to an hour city drive.
I have a 2600 with sprung hub 6 puck disk and I agree with Stevie, best clutch I've ever driven. It gets a little chattery at first, but once you get used to it its not a big deal at all. Engagement is quick, but not unmanagable by any means.
The other alternatives I'd suggest follow Jason's, go with a Zoom. They are Fidanza rebrands. The Fidanza stage 3.2 is rated at 395 ft lbs and is only $340
here where its Zoom counterpart is $330
here. The Fidanza 4.3 is rated at 464 ft lbs and is $365
here and the Zoom counterpart is $360
here. For reference, from Modern Automotive Performance the sprung 6 puck 2100 is $345, the street disk 2600 is $437, and the sprung 6 puck 2600 is $432. Hope that helps.
I should also note that you should check prices between SBR, Extreme PSI, and MAP. MAP is substantially cheaper, and is on pretty much everything they offer for that matter.