I can make the decision easy for you.
NetApp marked Flash Accel as End Of Availability on March 13th. So you do not have the option of deploying it any more. The downloads are no longer available and existing installs will not be supported after this year.
Funny as they had released a brand new version (1.3) only weeks before and were heavily touting it as a central part of their virtual storage tier.
No explanation or warning, and for customers like me who just purchased tens of thousands of dollars worth of SSDs with a goal of utilizing this technology, a bitter pill to swallow.
http://support.netapp.com/info/communications/ECMP1516733.html