My bike uses the same engine, I've had a true 75mph and it's dead standard, I've only changed the gearing.
Brilliant little lump, over 100mpg easily and still pretty entertaining!
Haha, I shouldn't be needing to touch the engine for the rest of my ownership. Internally at least, the outside I clean and maintain the chain etc.
I was considering selling or swapping for a 4T as they're more reliable, but I'll be on a big bike next year so absolutely no point for me to change insurance over etc for the sake of 6 months or so.
Personally I would never get a 125 4T. Reliability and two stroke doesn't bother me. It's a couple hours work piston and rings. At least when the engine does give up it's peanuts to rebuild
I got very tired of the bike throwing b**ch fits, especially when it meant having to get the train to college/work...
For what I use a bike for (commuting/leisure/greenlaning) I would go 4t over 2t any day of the week