When I was in my "lots of crunchy rules, don't care about how much it slows down the game" phase (back the mid 1980's), I loved RoleMaster and SpaceMaster. But, when I started to move toward smaller, more minimalist game systems, MERP (and, later, Cyberspace) were a great fit for that.
More minimal, yet a lot of the same ideas in overall system design. Yet MERP and Cyberspace (CS, which is the same rule set, tweaked for cyberpunk) weren't completely minimalist. It was a good balance. But, then, true minimalism isn't barebones. It's "what is necessary, and nothing more". But some people forget that it's also "nothing less." That's what MERP/CS were, in my opinion. What was necessary, nothing more, nothing less, with a very similar flavor to the far-from-minimalist RM/SM.
With some tweaking and expanding, you could use Cyberspace as a SpaceMaster replacement. With a little more tweaking, you could combine MERP magic rules, spells, skill group, and profession, into CS... letting you run Techno-fantasy settings like Shadowrun. Further, the way professions were implemented, it was actually pretty trivial to make hybrid professions and/or entirely new balanced professions (you just mixed around the skill points per skill group per level, recognizing that one of the groups costs twice as much).
In that regard, CS/MERP was almost a holy grail of RPGs. Except that, by the mid-90's, most of it was gone. And when the new Iron Crown finally got around to addressing the lighter-game counterpart of RM/SM, they didn't resurrect this great system. Instead, they created HARP. Don't get me wrong, HARP isn't awful, and it has some good ideas... but it's no MERP. I had a lot of hopes for HARP, and it didn't really live up to them.
To see comparisons between "RMU Beta" and MERP is kind of a nice sign, in my opinion. It makes me wonder if the new-edition of MERP (mechanics wise, not settings wise) might be on the horizon. That would be a good thing. But, it makes me wonder about what place HARP has in the product-line ... because anything that fills the shoes of MERP will be a competitor with HARP. (MERP is even a little bit lighter than HARP)
So: am I an older gamer, yes. But that's not why (over the last decade, but not much in the last 4ish years) I have sometimes chimed in about MERP. The reason I chime in about MERP is that it was a particularly good system for those with a particular mindset about RPG rules and minimalism. In the same way that there are still gamers that play 1st edition AD&D, and even a recent resurgence of original D&D and 1e AD&D players (the "old school renaissance"), there are some gamers who are still nostalgic about MERP/CS.
I even did a version of FUDGE that was heavily based on MERP/CS, quite a while ago (similar structure of skill list, and how you bought skills and spells). Unfortunately, I muddled it down in an action point system that was even more complex than Hero. And then d20 came out. By the time I got back to FUDGE, I was going in a completely different direction. These days, I'm more interested in the game "Warrior, Rogue, Mage".
But, this thread alone has gotten me over the "will I or wont I pick up the RMU Beta" question. If RMU is drawing comparisons to MERP, it's worth looking at.