Take a look at the post below from Stargazer’s World. SFA is a retro clone of Lord of the Rings, which was a simplified MERP which was a simplified RM.
I don’t see SFA as a direct threat to RMu. It is an 18 page free pdf game. The biggest threat is that these games, like vsDarkmaster as well, take away every unique selling point that RMu has. Criticals are commonplace now, detailed d100 systems are not uncommon thanks to ‘powered by Zweihander.
The last thing that RMu has is in targeting experienced GMs by being too complex for beginners. Not the best selling point possibly.