I have not tried RMU in Roll20 but we have done Shadowrun and 40K Maledictum with character sheets and die rollers, push button skill checks, calculators and critical tables built in. Makes the game run extremely smoothly.

RMU on VTT with attack tables makes things super fast.  if you do AP tracking, it's like 2 clicks per phase (1 for you action, 1 to end turn) with 1 click to attack.
If you do faster rounds - well it's just click attack and end.   Super quick.  The system does the rolls, scales the damage, rolls the critical.  Piecemeal armor, injury mods, etc are all handled. 

The first roll for a session is a little slow (~2s) as it needs to download the critical tables. ;-)

A piece of advice for people that aren't fully familiar, I tend to run two separate open windows - one for the character sheet and another for the table top layout/maps/etc. Popup boxes will come up in both windows and if it is under something like the character sheet I dont have to worry about trying to figure out why I cant find it as it is visible on the Table Top window. Clicking between the screens is not hard or if I am at my home set up I use two screens. If I am running I tend to use 3.

I agree with all of that.  If you have a single monitor using a tab for your character is also a great improvement.

So... being as it was recently Tuesday (the forums were down at the time for me)... we have an update available!   A pile of little bugs this week.  Work on improving equipment, custom professions and making the charactermancer harder to get wrong.

So a number of fixes to custom professions.  Also a bit of work on improving knacks in the Charactermancer.  And of course the usual pile of random bug fixes.

- Knack selection now respects power levels.
    - Still don't support 'set to average' and # stat boosts - a future update
 - Knack and Profession Bonus won't continue until you select all items in charactermancer (this has impacted a few of my players... so make it impossible to continue until it's correct)
- Subtle now works for 'A' spells (0; it's not really a thing that happens)
- Always apply armor casting penalty - even if you don't have transcendance  (this was funny; if you didn't have transcendance you never got an armor penalty for casting... buy 1 rank.. and now you do, modified by your transcendance).
- Update treasure law armor to include material
- Armor: Make sure we use the material if supplied
- Fix armor metal vs other materials
- Make sure ranged penalty is always a penalty (was sometimes providing a bonus... uhhh...)
- Creatures now roll $Realm RRs, not 'undefined RR'
- Partial Dark Mode; not quite usuable, but you can look.
- Custom professions
  - Save weapon costs correctly.
  - Save the correct Knacks/profession bonuses (@nef)
  - Fix level up spell lists (improves Roll20 Characters too)
- Handle Superior Item drops (@bambo)

I have tried pretty hard to hide most of the complexity of Rolemaster.  Skills/stats/RRs/DBs etc do all the calculations for you.  So you see the ranks and the bonus on the sheet (you can hover over a little info icon to see more details; how it was calculated). 

Rolling a skill becomes as simple as clicking on the bonus and it shows the results.  Or you can click on the little dice  and a roll20 popup appears and you can add modifiers.  (note it frequently pops up behind your sheet - I wish I could fix that).  And then it rolls with the modifications.   Casting spells is simple as clicking on the spell name.  If it's an F spell or I spell the appropriate RR targets are also shown.

Attacking is a two step process - first select you target; then click to roll your attack.  If you hit the victim then clicks "apply" and the damage is applied to their character - injuries, bleeds etc all applied.

Is there any specific questions you have about it?   

Generally I think it's fairly easy to use.   And I have been trying to improve things based on feedback.

If you like DM me privately and I can add you to a test game where you can try cahracter creation and other things.

I'm particularly worried about the general interface of roll20, and I think adding Rolemaster to the mix might even make it more complicated. But I'm wondering if anybody is actually tried it, and whether or not they like it!

Anybody want to weigh in?

SpaceViking

Diving deep into RMU Treasure Law I started producing finally a very detailed podcast review in 6 parts- https://drive.google.com/file/d/1XBrILmv75B-2K8MjG7Ui9cIlPJQ49h-y/view?usp=drive_link
Have fun!
Micael