RE: Do you suggest the OS FL-70 4str.?
Kostas, I helped set up the only one flying at our field. I had reservations due to the airbleed carb and the lower price point.
To my surprise, it ran quite well out of the box and took about three tanks of fuel to settle down into a reliable 2200 rpm idle. Once it settled it proved to be a very reliable engine.
It pulled a consistent 10,000 rpm with an MA 12x8 K series, so it had quite reasonable power too.
It actually had quite a bit of character - its exhaust note is quite distinctive, seeming to be a little "deeper in tone" compared to other engines its size.