I remember them being a bit finicky on enclosures but if you could get it right they sounded great. Really efficient speakers. It’s too bad the foam used on the GE series mids was so thin & prone to degradation. Always thought a nice red butyl surround would have been the perfect compromise between efficiency & longevity for those.G&S, forgotten by most. Some of the best stuff I heard back in the day had G&S speakers. There's a local guy who did some amazing builds back in the 80's-90's using G&S speakers including the Redline subs and their mids and tweets paired with HiFonics VII and VIII amps. I had a quick tour of his NOS G&S stuff in his shop a few years back... he has tons of it and it really brought back memories. I have a handful of their amps, also excellent. It's been years and years and I can't remember who they contracted with. PPI if I recall but I'll get around to cracking some open one of these times and check them out.
I did have a bit of an issue with the glue separating from the cone & spider on the BD series as well.
You’re correct about the Competition amps. Think it was the PPI AM series boards they were based on.