Exton made the mistake of repackaging other people's work (which is freely available) as his/her own and then tried to sell it (though apparently the latter is no longer true for RaspEX). This "OS" does not provide anything unique which can't be found and put together yourself. With a little bit of effort it's possible that you might actually do a better job and have an OS you can upgrade without breaking it. RaspEX might have GPU/HW acceleration added when the Anholt VC4 driver and kernel support are ready, but it is doubtful it will happen any other way. Have you tried Debian Jessie or any of the available Ubuntu versions/flavors on your Pi2B? They all perform very well from my perspective.
I've tried Debian Jessie, Ubuntu 14.04, Ubuntu 14.10 and Ubuntu MATE 15.04 on the Pi2B. I have nothing more to offer than my anecdotal opinion, but Debian Jessie has been performing best for me.