Who was it who made a frame out of AerMet 100 and was it any good?

Arrow racing in the US made an Aermet frame IIRC.

All I remember is it was touted as being super strong as it's designed to take stress like this as undercarriage landing gear.

Dean wasn't it?

If you like the science, here's a very interesting series of articles by Scot Nicol; though these are over 15 years old.
Since then, Aermet 100 frames have been shown to have a high failure rate.

I've been looking for one for a couple of years and IIRC there have been just 2 on ebay in that time.