given that you want to do architecture photography and switch to a DSLR eventually, I thought I would share a different approach to choosing you camera.
First, I would suggest that if you are interested in this field to always use a tripod (even the pocket version might work). Architecture photography requires great detail and you often shoot in the morning or the evening. With the limited light hand holding your shots is very difficult and unecessary. The building is not going to move so why not take advantage of that situation. So I would not make anti-camera shake feature a big consideration and rather spend that money on a quality tripod.
Secondly, you suggested two DSLRs and they will both do a fine job. The Nikon D7100 has actually higher ratings than the Rebel T4i:
but in the end they will both suffice. The much bigger question is which kind of lens you are looking for. Traditionally, the professional choice for the canon would be EF 17-40mm f/4 from Canon http://www.usa.canon.com/cusa/consum..._40mm_f_4l_usm
if you want to go with a lens specific to the smaller sensor then I maybe the EF-S 15-85mm would work:
. You actually mentioned that you like zoom for architecture which is a great idea when you want to detail shots. However, wide angle shots are much more challenging to the camera and lenses. Often if a camera can do a good job in wide angle it will do a great job zoomed (given of course some mid range telephoto lens).
So, if you want to go the DSLR route and are interested in architecture photography, I would approach the decision by first checking out some good tripods:
then looking at some lenses:
and then figure out which camera makes sense in that setup.