I've never shot a "Major 9" before, and never owned one. However, reports I have from talking with gunsmiths and shooters in the US that use/build them regularly is
a) It is very hard on the brass. You get about two firings out of a case before the primer pockets get so loose that the primers fall out. That's okay, you never pick up the brass anyways. Keep in mind that they have a much greater supply of cheap 9mm brass than we do.
b) Extraction is the key. It is very hard to get an extractor tuned perfectly so that you get consistent ejection. One gunsmith goes so far as to say that the sideways scope mount is preferred otherwise you can get malfunctions during ejection. He says that as many as 1 out of 5 of the guns he builds may have some extraction problems if a sideways scope mount is not used.
c) Performance does not seem to be appreciably different from .38 super given the wide variety of powders and bullets now. Sure, you can never get enough powder in 9mm major to make multi-port hybrid guns work as well as a super can, but there are many super guns out there that don't even use hybrid ports and still function fine.
Other than the cheaper brass, I don't see any advantage of the 9mm Major over Super, and once enough people move over to Major 9, the brass ain't gonna stay that much cheaper for long.
1911 vs 2011.
I don't know why anyone would build a racegun on a 1911 frame. If you ever go traveling and shoot open outside of Canada, you'll be at a severe disadvantage.