You'll love the 4-strokes. The mixture adjustment is no different that a 2-stroke other than it can a little more difficult to set "by ear". Once it is set you will likely never have to touch it unless there is a big temperature change. Best part is the great sound though.

Many people claim that you need really high nitro content fuel but I run 15% Cool Power in all of mine and they run great.

I've also never found tight valves on one yet but if you have a basic understanding of engines whether it is from working on cars, bikes, mowers or whatever, you'll have no trouble maintaining an RC 4-stroke.