SSD caching, single or seperate drives?

[TheScirus]

So I've looked at all the reviews and test of the z68 SSD cache feature but no where is there a review of using 2 SSDs (One for boot, the other for HDD cache) or using a single larger SSD, say a 256 GB and allocating 64 Gb as cache. What would you guys do?

I looked at getting 2 M4s - 128gb for boot, and a 64gb for cache = about $390ish

or a single M4 256 GB at 460ish dollars, gain an additional 64 GBs for boot an use the other 64gb for cache

 

[Leaps-from-Shadows]

What would I do? Buy the bigger SSD and just use it as a normal drive with the OS and your most-used programs/games, and have the platter hard drive for the rest. In other words, I'd ignore the Smart Response feature entirely.