I have Majora's Mask on the VC (also PAL), and I compared it directly to Majora's Mask on the N64 and Ocarina of Time on Collector's edition (runs at 60 hertz). Findings:
1) Majora's Mask (MM) on VC runs at 50 hertz, unable to switch to 60 hertz for PAL users, just like any other PAL VC game.
2) Framerate of MM on VC for PAL is ~22 fps. That seems low, but the speed is corrected on the VC, so there are no framedrops or lag. If you use component cables, the game feels smoothers than the N64 game (because the signal is digital instead of analogue).
3) Framerate for NTSC users (60 hertz) is ~27 fps. That is a 5fps boost, but it runs at a lower resolution (640x480 instead of 640x576 for PAL).
4) Yes, there are some minor sound glitches in the VC release of MM, but it's so minor I can't believe you really notice it. The Collector's Edition of MM on GameCube was much worse, with constant sound loop errors and stuttering.
5) MM on VC runs at a better framerate than MM on the Collector's Edition.
6) MM on VC (so far) is entirely stable, no crashes or freezes, weheras the Collector's Edition had constant crashes and freezes.
All in all I'm very happy with Majora's Mask on the VC. It looks very sharp with component cables, and runs a little smoother too compared to the original. This is how Majora's Mask was supposed to be on the N64. It didn't age at all and I'm still impressed by the graphics and music.