Wilwood Superlite rear internal drum disc worth it?

Hey all,
Pretty simple question, hopefully provoking lots of opinions. As I can't continue to use my Baer rear parking brake due to clearance issues with my EvM kit, some other guys here have turned me on to internal drum rear discs like Wilwood. The question is this - should I go with the plain-face 12", drilled/slotted 12", or 13" plain-face or drilled and slotted here:

http://www.jegs.com/p/Wilwood/1014187/10002/-1/10155

Is it going to help at all to have a 13" rear as opposed to a 12"? The Dynalite 12" here seems pretty good but doesn't come with slotted only discs as an option. My front 13" Baers are slotted only and I'd like to keep the rears that way too. I don't believe in drilled but think slotted is a good idea to keep the pads shaved even.

http://store.summitracing.com/partdetail.asp?autofilter=1&part=WIL%2D140%2D7143&N=700+115&autoview=sku

Are 13" really going to help any more than 12" on the rear? The Superlite seem to have more swept area, but both are 4-piston.

Bullitt, thanks - the advice about number and size of pistons helps. I imagine the pistons on their 12" are smaller, since the size of the calipers is smaller and there are still 4 of them, but I'll look into it. I wish now I went Wilwood in the first place, but I was drawn in by the ease of finding pads for the Baer/PBR/Cobra calipers. I could see a point in the future where it might be hard to find Wilwood pads. I'd hate to go with one rear 12" kit and later go to all 13" later on, but I just can't afford a full 13" kit right now. And the 13" kit wouldn't work with Degins' spindle, which I need since my upper ball joint pivot interferes with my 4.75" BS 17" wheels.

I love how every single upgrade has a multipart story to it. Restomodding is like an intricate puzzle . . . or maybe a Rubik's Cube is a better analogy.

yeah, I thought about going the Exploder route, but the regular Wilwoods are pretty reasonable and their polished caliper looks close enough to the Baer to look good from afar. The 12" discs are close enough to matching the 13s up front to not look too out of whack and will fill up the wheels fairly well. Most likely the 12" rotors are a better match, that might end up being the best short-term solution. I can order that kit as an option on my Currie rear, I just didn't want the brakes to hold up the 9" rear that I put in when I do my 408.

Engine, 9" rear, and rear brakes are a lot of $ to swing at once, but I'm not comfortable not having an e-brake or other "plan b" for long, esp. with all that power. It's a shame the EvM rear interferes with my Baer parking brake, but who knew?

yeah, on the current system I have the Baer MC that ships with the kit and haven't had any issues except for pedal box flex. I plan to upgrade to the transamracing power booster that lets you use the manual brake pedal, but that kit has been out of stock since the dawn of time as the Mark (nice guy) waits for his plate to be made by some couldn't-give-a-damn aerospace supplier. It's been at least 9 months or so, and I call every month and get the same answer . . .

I'll probably go with the 12" kit as it meshes better with my current setup and power booster plans. I'll just take an if-it-ain't-broke-don't-fix-it approach - 13" Baers and 12" Wilwoods on the rear should give me plenty of stopping power. The Baer pads and calipers don't even sweep the whole area of the rotor, so the extra inch is just to fill out the wheels and give a little more cooling area that is unswept . . .

please post your impressions here anyway in a couple of weeks, I'd like to see it, or point to another thread if you've got 'em on there!