Personally no. Although if you consider SWTOR was built using HeroEngine and a vast amount of MMOs have launched on BigWorld they should be completely fine for a one man team. They are specifically built for this type of game and provide the tools you would otherwise spend a few years building.
Is there any way to try it out, before you pay 99$?
Entropia Universe is using CryEngine 2. My PC is too weak to run game even on lowest settings, but Crysis 2 works fine on lowest setting (which is normal if I recall correctly)
