Istarted off on a 750SS way back in the days and am now on my 3rd 748 with a Gixxer 600 in between. On the road nothing between a 748/916, it'll be the rider that is the difference. Reliability issues are not a cause of which bike it is, rather who has owned/maintained it before (or not). My 748s have all been faultless apart from not being crashproof!!!
After a 750ss any 4 valve bike is going to be a revelation and will make you wonder how you managed with so little power before. I'd go 748, cheaper to buy (relatively), cheaper to insure and slightly easier to adjust to after a 750ss. Give it a year, get used to it and see if you need a 9**. Chances are you might just stick with it.
Sound advice above though, 'the best that your money can buy' with a 'proven' FSH, haggle away, it's definately a buyers market at the moment. Good luck
