What kind of problems are you having? Or do you mean it just feels slow because it's a 4 stroke? Would you recommend 2 stroke for a 50cc engine?
I have Agility 125 and People 250S and if I could choose and was restricted to 50 cc, for sure I would go with 2 stroke and I would probably check how many kW the engine develops. In that case, I would probably forget Kymco and go for Italian scoots as they develop 5.5 or more hp, which is twice the power of 4 stroke 50 cc.
For me, but that is just me, 50 cc 4 stroke is not acceptable, I have 240 lbs and have 13 km from home to work that include 17% downhill/uphill parts.
However, I must add that I do not know if Kymco has 5 or 6 hp engine in some 50 cc 2 stroke model.