SchizTech :
Technically that's not a 5th gen part. That's the "enthusiast" variant of the fourth gen or "Haswell-E." The 5th gen "Broadwell" parts out so far are only low-end "Core M" parts.
If you feel you need more than a quad core you can get 6 or even 8 cores (for mucho $$$$. The top end i7 goes for $1k. Even lesser end 2011 socket parts go for many bones). Also a socket 2011 board would be needed, and those tend to cost more than mainstream socket 1155/1150 boards.
If you don't need extra cores, don't bother. The performance difference per core isn't big.
I'm kind of with you on this, except with one thing- the performance
is pretty big, depending on what you're doing with your computer.
To the OP- the motherboard I would use, in a low budget X99 build, would be something along the lines of the
MSI X99S. The only real downside with going X99 is that you are forced to spend the extra on DDR4 memory; but the cost difference isn't all too terrible.
Here's a couple of build sheets I made, based on the the 4790k and the 5820k, to compare/contrast the cost difference of a somewhat comparable Z97 and X99 build. The overall cost difference isn't too terrible, but it also is pointless to spend that much extra for the "average" user.
Z97 build, with 4790k-
http://pcpartpicker.com/p/RkTPYJ
X99 build, with 5820k-
http://pcpartpicker.com/p/PXHRHx
The base prices, as of writing this, vary by just under $400. For the speed increase you get with the DDR4 memory, the extra PCI lanes (great for heavy SLI users), the extra cores, and the quad channel memory option(available in more expensive motherboards), definitely can give the end-user some dramatic performance increases. Not everyone will benefit from this, but it's definitely a
huge step forward in the way that computers are being built.