Well, it looks like you
can discuss such matters outside of the restricted subforum!
Up to a point.
There's one thing no one has said so far in this thread. While you need L2 certification to fly EX under Tripoli rules, you can get access to the Research subforum with only L1. So if it's talking about it that you're interested in, L1 will suffice.
Finally, though I know it's not altogether satisfactory (or even close) you can certainly post things like:
I tested my new EX motor today. It worked, but not up to expectations. I should have got about 400 Ns and 150 N average thrust, but I only got 300 Ns, and the thrust averaged 90 N. I obviously need to increase the burn rate.
Chewing the fat isn't as exciting as burning it, but hey, it's something. (Yes, I know, a fat and oxidizer formula would probably never be allowed by Tripoli, and probably for very good reasons, like it melts in the case.)