i have one, its great but i would consider other keyboars around the same price as well, (im in the UK so price may vary) - i would look at the juno g (for 100 quid more here in the UK) maybe a second-hand alesis fusion? there are plenty more cant think at the mo
or alternatively your setup could be a midi controller and a bunch of vsts/sound modules.
anyway, whatever you decide i suggest thorough research!!!! tweakheadz.com should help
BTW - i hope your aware that the x50 does not have a sequencer!