I noticed you were in the UK, and you mentioned that even maintaining a 2 stroke give you troubles.
You should check the cost and availability of parts, and someone to perform the labor, if you are not skilled enough to do it. 4 strokes are fun, but they do require frequent oil changes, and you have to check your valves. This is a simple task for someone who knows what they are doing, but can be a headache to perform, or pay someone else to do if you are not comfortable with doing it yourself. Personally, I can't afford to take my bike into a shop, forcing me to learn myself. And a total lack of a qualified sop in my area for my 4 stroke, forces me to learn really quick.