I have no idea about the fat content of hamsters compared to mice, but with pinkies - all pinkies are fatty, the goal is to get them off of pinkies and onto fuzzies as soon as possible.
I suspect (note that I don't have proof and don't claim to) part of the reason why corn snakes stay small for so long until they hot 15 to 20 grams and then start shooting up in size is because of the lack of calcium in pinkies compared to fuzzies.
So - mouse pinky, hamster pinky, probably no difference whatsoever. Get them onto peach fuzzies as soon as they are big enough and then watch the growth explosion.