I say you can't go wrong with the new DS4. Since the DS3 the conrod issues are a thing of the past, and the piston liners were already very good.
The performance of the DS4 is now back on par with the top engines of other makes. When you factor in the price it get's even better!
Hey you may end up liking it so much you start using it for more than practice!
Team Serpent, Xceed, Sanwa, LRP