When I owned 99 Bounder with a V10, I drove it over 35,000 miles including trips to Florida, Texas, Iowa, Colorado, Washington and Alaska. That is to say it took us over hill and dale without nary a whimper. True, in the mountains, it would really wind up going up some of those passes but never gave us any moments of concern.
The guy on the radio may have been talking of one isolated incident with a V10, but that could be the case with any engine or vehicle. I believe the vast majority of owners of the V10 engine will say they are very reliable.
If I were looking for an RV with a V10 and I liked the floor plan, and everything else checked out, I wouldn't hesitate to buy it.
That's my story and I am sticking to it
Happy travels. Arnold