Yes, I've been thinking about it and in the book from the couturier it's explained that in couture there's a lot of manipulation of wool by using steam by stretching it into shape and that would be really difficult to do with gabardine as it's water resistant so wouldn't respond to steam in the same way. So it probably depends on application, this is the confusing thing with sewing, I find.
Also the idea that something is lightweight, ergo not as good isn't always true either, it'll be good for certain applications and not for others. My brown linen dress I made last year could have been a bit lighter (but not the M&M weight, I think that's more lightweight blouses territory).
And I agree colour choices are a consideration too, I really need to contemplate experimenting with dyes but I'm fairly convinced I'm going to end ruining the fabric in the process...