is a tricky one, coming from the bandit the CBR600 should be quick enough for you. and as long as its the RR its still one of the nicest looking bikes around. it will also hold its value well and age well.
The gixer is a whole lot more fun though, the engine is a stunner, and handling should be spot on also, both bikes would really benifit from spending a few £ getting the suspension freshoned up. if you are riding all year round you will really have to take take of the gixer, the british winter just turns them into old hacks in no time, its shocking.
you are defo doing the right thing is testing them both, just get the bike that you feel you could live with. Iv always been a yamaha/kawasaki man myself, just the seating position of susuki's dont seem to suit my lanky frame, and every honda iv had a blast on have always been so dull. I would certainly add the 636 and R6 to your list, the R6 in particular is a hoot, the engine is a stonker on it.