Hmm . . . I think it's mainly a weight issue: the Merkurs are like a modern BMW or Audi 4x4, very solid and heavy. The old Gillettes (even the Fatboy and suchlike) are more like old classic sportcars: nippy, agile, throw them round the bends. Not really fair to compare them. But you are right in principle: a sharper blade in a lighter razor can be a great shave (all cut and no pressure).
Second, there's the angle issue. They do require different wrist positions and the one you first learned with is likely to be the memory muscle of choice and feel most natural. The only way round this is to stick with one razor until it is comfortably giving close shaves and feels second nature, then return to it from time to time to remind yourself and refresh your technique.
HTH, just my 2c
Gotta dash!
Ollie