I have no doubt that the P-51 scored kills on a few migs. I have read stories about it and find it very intresting. Is this the F4U you were talking about?
F-51's in Korea weren't officially credited with any MiG-15's, nor did they actually down any as far as I can tell. In a few cases MiG's were claimed but not officially credited and those are included in some books and listings, but in all the specific cases I know of, the Soviets recorded combats with F-51's that match but didn't lose any MiG's. Per the USAF's 1953 Statistical Digest 8 F-51's were lost in air combat in Korea in the period of MiG-15 activity.
The MiG downed by Folmar was confirmed by the 1953 NK MiG defector's accounts, as being an NK a/c. Besides Folmar's a/c, two USN F4U's were downed by MiG'15's on the east coast of Korea during 1952 (the Folmar action was on the west coast). NK accounts also indicate those were their a/c, so coincidentally all the conclusive F4U actions were against NK MiG units, though those were relatively rare opponents in Korea. Soviet and Chinese units each also claimed a number of F4U's in actions also recorded by the USN and USMC (sometimes as F-47's or even as F-51's) but no F4U's were actually lost in any.
As is well known, an FAA Sea Fury was also credited with a MiG-15 in 1952. Those opponents were Chinese, but available Chinese accounts seem to deny they lost an a/c in that combat.
The MiG-15 and Me-262 were hardly comparable in performance. I think the point is just that in something like endurance the P-51 was still greatly superior to the MiG-15, also to jets long after that in practical combat radius w/o aerial refueling, but by Korea the MiG's superiority in speed made that moot as far as using the F-51 as a real fighter.
Re: acceleration between jets and props, even besides the issue of throttle response of the early jet engines, the thrust of a jet is inherently approximately constant with speed, while the thrust of the prop disk of (especially constant speed controllable pitch) will increase as speed decreases, so a prop with similar power to weight ratio as a jet will accelerate better, and have better 'vertical plane' performance at low speed. This effect is washed out by the enormously greater power to weight ratio's of later jets, but in case of WWII jets the props would out-accelerate them at low speed, and it was another whole new category of disadvantage for the jet to agree, or be forced, to engage the prop at low speed, more than the advantage given up by say a P-51 agreeing to engage an F4F at low speed.
Joe