When I had 325 hours, I found it a big struggle to fly a Cessna 206
I actually doubt that you were having "a big struggle". 325 hours is getting along in experience.
The thing is that pilots progress in training at roughly the same pace regardless if that training is on a fighter jet, large airliner or small piston. Small pistons are used because they are cheap - not because humans have any innate need to gradually progress from smaller to heavier/faster types.
So - if your training is airliner focussed, as it is in the MPL, you are as good at flying an airliner at 200 hours as a GA pilot is at flying a Piper Warrior at 200 hours. (And you have the added benefit of an experienced pilot next to you, and better SOP discipline.)