It's a 600Mhz base clock difference! ^.^
To be honest, for the extra
$10 or $15 that it costs for the k variant, it's most definitely worth it, if not only to increase the resale value a few years from now.
An i7 will get quite hot with the stock cooler regardless, so picking up an aftermarket cooler was probably going to happen anyway.
For for the price it's a great deal, it leaves options open for future builds should you decide to overclock to get more performance out of it. Even if you don't overclock (It's not entirely clear whether you do or not) I'd still recommend picking up the H7 and a 6700k for an extra bit of cash.
Edit: Just noticed that the 6700k is not in fact $15 in price difference, was basing this off a price I saw yesterday for it!
Assumed it would be the same today, apparently not.
Get the 6700 non k if you don't overclock, should be very similar performance.
I still recommend picking up the cooler regardless.