Is an M7 signifcantly faster than an M6

[ray_g]

I don't know about that. Certainly the M7 shutter is more accurate, than the mechanical version, but professionals did shoot slidefilm with M cameras for decades without a problem.

Maybe its an issue for product shots, but then again pros shot plenty of that type of work with the good old mechanical Hassy.

I don't agree with the opinion that it is impossible to shoot slidefilm with older mechanical shutters and no AE. As you said, the pros have done it for years, for instance, for NG. They also had to bracket like crazy and went through bricks of Velvia for a single assignment. Not to say that you don't need to bracket with a "more modern" camera.