This is a picture of my RMX book ... and my katana.
I bought Rolemaster Express based on a blog or forum series that I read nearly two years ago. In it the author tried learning RM by using RMX, having only played MERP prior, which sort of mirrored my experience at the time.
So I checked my local used gamebook store and online. I found it at Amazon for a reasonable amount.
Now, I will tell you why I consider taking my katana and putting it through my book whenever I look at the book since receiving it because of major deficiencies and unavailable supplements.
First of all, RMX is not supported due to a falling away of the author several years ago. The books are only available currently on the used book market.
Next I go to the actual content and compare it with MERP
Second is the number of playable races is only four in the main book - humans, dwarves, elves, and halflings. MERP had Dwarves, Umli, three types of Elves (Sindar, Noldor, Silvan), half elves, hobbits (Stoors, Harfoots, and Fallohides), 12 types of Man, Variags, Woodmen, Woses, Common Orcs, Uruk-Hai, Half Orcs, Trolls, and Half Trolls.
I believe that RMX had several more races released in supplements, but good luck finding them!
Third is the number of playable professions is only four in the main book - fighter, thief, animist, and magician. MERP had warrior, scout, animist, mage, ranger, and bard. The missing two professions ranger and bard, were really fun in the games I played back during MERP. And trying to play the game without them may be more difficult.
Fourth is that you have to deal with 10 stats instead of the 6 stats of MERP. The additional four stats do not add much to the entire game. And most of the skills are based on two stats not like one in MERP.
Fifth is that half of the spell lists are missing about four spells in their lists, unlike the complete lists found in MERP.
Sixth is that the included encounters in RMX is only 21 monsters. MERP had 31 monsters and 36 common animals.
I advise any former MERP GMs and players not to purchase RMX and to ignore the old advice that you see elsewhere.
Two years ago, I did join the RMU beta 2 test and tested that system. I gave what advice that I could in hopes that the final game would be usable by former MERP users. We'll see how much of the old complex and unappealing RMC, RM2, RMSS, and RMFRP bloat and unnecessary complexity drips back into the final version.