It is very good idea. x-fast ram will help your ssd live longer. It will work that way: first chache will be x-fast ram and most of disc operations will be done in x-ramdisc so your ssd need to do much less work = longer life.
It also depends on how much RAM you have installed in your pc. imo 16gb is minimum to effective use of x-fast. In my pc i run x-fast ram set to use 8GB of mem, so another 8 is free for system.
I dont use ssd at the moment (i want to buy it in some near future).
IMO: You should buy AsRock mb, maby think about buying inter CPU (its faster than AMD and I think 4 cores is enough for today and probably for near future, also intel cpu = less heat, need less power...). and get 16GB of good memory, I choose kingstone hiper X series CL 9, 1866Mhz (i dont see any speed improvement in chooseing higher freq. ram becouse latency is really going down).
Look at the mobo i bought: Z97 Pro4 (I saw that you use ati gpu and this mobo work in crossfire) LGA1050 (for new refresh cpus from intel - they are priced same as "old models" but are clocked a bit higher) m.2 socket for fast ssd.