Don't know about the SD cards from Sandisk, but the new Ultra II and the Extreme III CF cards are both the same speed. I think the Exteme III has been dropped.
(at least from the CF line..). I also don't know that a faster card does anything for a T2i...it's buffer speed, not card speed that seems to make a difference in how fast and for how long a high speed shooting burst will last.
I agree completely with the "less is more" concept regarding storage. 2x 8GB cards cost less than one 16GB and makes more sense. 4x4GB would be even less money and be more convenient as far as keeping track of where files are.
I have read the rationale about why a 32GB card is great so HD video can be shot for a continuous hour (or whatever). I was in the motion picture business a lot longer than most here have been alive. But my word isn't needed...watch any movie and see how often a scene is continuous for more than 6 or 7 seconds. It happens, but it's the exception.
The only good use for an hour of continuous video is to get guests who have over-stayed their welcome to leave by boring them to death by showing any home video that goes on for more than two minutes. (which happens to be how long an 8mm spool would run in total....and two minutes is an eternity when watching home movies/videos of another family's kids or worse...an "art film" by someone who thinks that an hour cut can be interesting..torture!!!!
AFAIK, the T2i is limited to 12 minutes of continuous 1080p footage. I've read this is due to a 4GB file limit on FAT32 formatted media.. other camcorders break up the clip into multiple files to bypass this limit. Ohhhh well