Compliance / Comfort? I would fit the biggest tires it would fit with the new wheel. run low tire pressure, it does makes a difference.
Weight? depends on your wallet. upgrade your current or buy a new lighter weight bike, both can and will cost ya depends on how much you want to spend and how light you want to go.
If you like your 595 and there's nothing wrong with it, I would stick with it. I (personally) don't think new bike is worth it unless it offers something that your current bike doesn't have / can't make it work / upgrade would cost about the same as buying a new one.
but then, a new bike is ... a new bike. if you can swing the cash, why not? haha.
just my $0.02
