i bought an r34gtt primarily because i cant stand the ancient r32gtr interior, and was also concerned about their age. driving the 34 and a mates 32gtr is a completely different experience, however i cant wait to get back into the 34 after being in his car, and there isnt really that much real-world differenece in performance between the two, besides the 32 having more modding potential, but if like you say, you plan to have it as a daily, the 34 is better in almost every way.
if i was you, id use your stock sti as a daily, the 34 gtt feels archaic in comparison to my 05 wrx, uses more fuel, and is probably slower though i cant confirm this as i havent had the chance to track it yet. but you do get a special feeling in the skyline.
also, after driving awd, be carefull in a gtt, they loose traction at a whiff of throttle in the wet, and are way to easy to slip in the dry too.
have fun.