I don't think smoke/oil coming out is a big deal. I have the same bike, just rebuilt the top end. Yamaha dealer helped me take apart the powervalve - they use Torx screws and are red loctited in from what I can tell. They saw nothing wrong.
The powervalves hang down at low RPM and divert some exhaust against the shaft that holds the valve and ultimately into the chamber that houses the linkage mechanism and vent hose. I've noticed smoke on other bikes, seems to be more on warm up then after.
Should be OK.