Novice i5 2600K build. Any feedback appreciated.

There are applications where the i7-2600K will be noticeably better and faster than the i5-2500K, but it isn't in gaming: http://www.anandtech.com/bench/Product/288?vs=287
I also can't see how it could be much more futureproof, because surely it will be many years before either needs to be replaced because of a lack of performance, unless games or whatever really start to favour 8 cores/threads any time soon. Which I wouldn't predict, but that's only my opinion.

http://www.xbitlabs.com/articles/storage/display/ssd-vs...
I haven't read this in awhile, but I remember that it showed that having more RAM has virtually no positive performance impact. Bit-tech (www.bit-tech.net), The Tech Report (techreport.com) and this site have done tests about the difference the speed of RAM has on system performance. I've only skimmed through them, if I read them at all, because as far as I'm concerned they are long winded ways of saying that you don't usually get noticeable performance improvements from faster RAM/more expensive RAM (outside of synthetic benchmarks). And even if the faster sticks do provide faster performance it is questionable whether the improvements are worth the money. Overclocking is another matter, if you want to overclock the RAM itself then yes the more expensive sets are more likely to overclock better.

Yea, those sticks are nice and low profile.