I read about 1000 posts on UCD's and what engines are flying them. I figure for my style of flying I want a 4-stroke and that a YS 61, Saito 72 to 100 or an OS 70 to 91 Surpass will do the job. The data I have seen shows they all weigh within a few ounces of each other. My number 1 objective is to get an engine that is easy to start and run and has ok durability. I would pay the extra money for the YS if it is easier to start and run, but not if its a little more hassle but more pwerful than say the Saito. Most of the local fliers won't think of anything but OS 2-strokes. One of my gurus loves Saitos. The other says they are junk 'cause his only one broke rods twice. He will have nothing but YS. What do you think? I want minimum hassle.