Hello,
I have 2 Rev 4's and absolutely love them. Oil changes do take a little more time, but no big deal. I have had one for 8 months and one for 6 months and I have not had any problems with either of them.
The gaskets on the head took a couple of weeks to seat fully and during that time I had a little seepage where the head joins the jug, but nothing major. It took me a little time to adjust to the 4 stroke since the last one I owned was back in 1973 (TL125), but I've been able to make my 2 stroke style adapt to the 4 stroke. I would recommend the Rev 4's highly!