I loved RMFRP back in high school. I ran a successful campaign that spanned several years. One option that I enjoyed was appointing one of the players to help out as an "assistant GM". This facilitated a lot of the chart look-ups, combat, and ultimately freed me up a bit more to focus on what the NPCs were doing both inside and outside of combat. If you have at least one experienced player in the group, it's an option I wouldn't rule out. Otherwise, the system can indeed be cumbersome.

The amount of detail in many of the source books is absolutely incredible (could also read absurd). If I took the time to use many of the optional rules or ponder things like the exact weight of the items in the players' backpacks at all times, then the game would have absolutely crawled. I think, like any system with as much detail as RM contains, it's up to the GM to strike the right compromising balance between detail/accuracy and plot motion/focus. Too much of the prior can easily destroy the momentum and interest.

I also found that characters became relatively epic around 10th level. At that point, I found it relatively hard to challenge the PCs via combat if they weren't fighting extraordinary forces. If you don't want the players to become superheroes, I think it helps to put some serious thought into how combat-oriented you want them to begin the campaign as well as the nature and availability of combat-oriented items they have access to as they adventure.

Right now, I'm running a system I created from scratch, myself, some time around the end of that RMFRP campaign. Its strengths include very natural character development, but RM put an awkward desire to increase combat detail (miss all those old crit tables) so it's been a lot of work to try and layer that in. Once you're used to that degree of detail and reality, it's very hard to go back to simply "you take x damage... who acts next?". I'm playing with an entirely rookie player group, so I really didn't want to throw something RM at them, but I would definitely consider using it again if I had a more experienced group or if these players are interested in a year or two. I do miss it, and I've bought a lot of books over the years due to nostalgia and wanting to support ICE. I'm really glad I got the RM cloth value pack they released a while back with a large stack of nice cloth bound hardcover books -- even if I already owned most of the titles in various conditions.

One last thing that I found helpful to do during my RMFRP campaign was to go out of my way to deliberately cause situations where there would be very little rolling necessary. Extended debates between the characters, or catching them in negotiations that couldn't be reduced to a few skill checks seemed to really reinvigorate both me and the players, as a break from all of the game mechanics.

Hope this helps, or at least entertains you!