Same bowl, thinner tank.
The only way this saves space from the wall, is if you also move the drain back 2".

Most 10" rough toilets do it this way.
Standard 12" rough bowl, with a space saving, or thinner tank.

Exceptions would be something like the TOTO CST744EF.10 which uses a 10" bowl and a standard tank.
Caroma 270 bowl has a swivel adapter that allows both 12" and 10"

But the only way to "pull" the bowl back, would be to move the drain.

This post was edited by terry_love on Sat, Feb 9, 13 at 15:01

I made a mistake on one of my bathrooms rough-in on my last house. I used Toto and have been very pleased with their performance. I used the standard 12" rough-in unit. Toto uses a separate trap assembly. It mounts to the floor and closet flange and you then set the toilet on it. I purchased the 10" trap assembly, did not have to change toilets and it gave me a graceful recovery from my mistake.

(x-post) - Thanks for your help (and your informative website/forum). Looks to me like the 12" rough-in version of that Toto (CST744EL?) remains 28" long back-to-front and maintains the same external shape, but the 12" rough-in version with the different bowl is specified to be a full 1-1/4" from the wall, even more toward the edges since it's curved inwards. I've got to believe the large gap would draw some customer complants, since many of use the tank cover as a shelf for toiletries and we don't want stuff falling behind the toilet.

Anyway, my renovation contractor wasn't sure until the flooring and drywall went in if I'd need a 12" or 10" rough-in, but now he says 12". He used a part near the wax ring (not sure what it's called) that pushes the 4" diameter drain pipe rearward some rather than straight down, to help clear a nearby floor joist underneath. I hope this doesn't hurt flushing performance. Anyway, this bathroom needed a short front-to-back toilet to allow the door to swing open more than 90 degrees - a 30" deep toilet would block it from opening even halfway. I settled on a Gerber Viper compact-elongated comfort height 12" which is only 27-7/8" from the wall. Gerber also makes a one-piece Avalanche compact-elongated that I would have preferred - it's 27-3/4" from the back wall and has better specs, but I found the bowl too high, 5/8" higher than the Viper's 16-3/8" which is about perfect, and the front rather than side flush handle is easier to reach when there's a wall surrounding it on both sides. I've used a 17-1/2"h toilet and my heels can't quite reach the ground - very uncomfortable. Anyway, the Viper is Gerber's midrange model, seems to have a decent rep but hope it works well. Not installed yet.

For another bathroom which is a new addition, I went with a Toto Drake 2 univeral height elongated, since in that room there's plenty of depth and the double-cyclone Totos seem to be the best thing out there, and the Drake II is the least expensive that uses it. In this room, the slender tank is nice because the sink and tub are both close by and a wide tank would make it look even more squashed into a smaller-than-ideal space.

Then there'a the basement half-bath which has plenty of space but where I'm willing to skimp some, since it isn't used often and a floor drain about one foot away that makes an overflowing commode less of a disaster than usual. Still, worth a bit more to get something good where we're not likely to have that happen. I'm thinking the standard 2-piece elongated Gerber Avalanche 1.6L 21-818 or 21-817 here depending on whether I need 12" or 10" rough-in respectively. Both are 16-1/2" height, and there's plenty of room in all directions. These are less expensive than a Toto Drake g-max or e-max, and from what I can tell flush as well if you stick to the 1.6g model. The current toilet is almost 11" from floor bolts to wall, and the tank is 3/4" from the back wall, so I'm not sure if a 12" rough-in will fit or not. I can see an outline on the floor of an old toilet that was 2" further back than the current one (which leaks when you flush it), which leads me to believe that a 12" used to be there but a 10" is now. The previous owner probably put up the tileboard behind it after the builder's toilet was already installed.

The shortest elongated-bowl toilet I could find was the American Standard Colony RightFit 2487.010, which is 10" rough-in, 16-1/2" high, and protrudes a mere 26-1/2" from the back wall. But I was reluctant to use it, as it's their low-end toilet with only a 2" flush valve; it flushes by dropping water from the thick rim, falling a long way before it touches the bowl sides, like a waterfall. Only 600 in the MaP score, but I haven't found that correlates well with real-life results. Are these any good?

Anyway, what do you think of my picks?