Add my 2 cents worth
AS350 not great but serviceable, retrofit good quality seat inserts
R44 shocking really with no adjustment, just find someone who can put in high density foam
R22 as above;well don't worry - don't won't fly them anymore
EC120 close to good just retrofit good foam and higher seat sides and
MD500 I put in the light weight mesh/military style and they were not too bad
but no adjustment, I think it is even worse than the R22 if you don't like the pedal position or are a bit taller its not much fun