You'll have a hard time finding an SL or FE for that kind of money (most are at least £1k more than that) but you'll probably find a decent (not mint) standard SS for that.
The only differences really are the single seat unit and high-level pipes but both can be found aftermarket. The reason SL/FEs go for more is that they have generally been better looked after as well as the rarity value.
They are not more maintenance hungry than a jap bike but respond well to a bit of patience with the setup.
The engines are pretty much the same as monsters of the same era but they tend to have lower mileage (tend to be fair-weather ridden rather than all year round like monsters) and should be very reliable. I don't know about the cylinder head bolts but wouldn't have thought they would have been changed.
Hi Sam, and Welcome. Was that you at Cornerspeed on Saturday?
I take it if you are thinking of heated grips you are looking for a bike to use all year round?
I found that mine ran poorly in winter and suffers from carb icing when it is cold and humid. My 750 ss has been modified so may be worse than some, but I do not think it is unique. I would definately consider this to be a fair weather bike.