The goal of Half-Life 2 : MMod is to enhance and expand gunplay, combat mechanics and the immersion factor by giving the Player more options and combat opportunities as well as refine how the Player handles his arsenal. Half-Life 2 : MMod also offers minor AI enhancements, extended abilities for combine soldiers, multiple bug fixes, enhanced visuals, VFX re-design, sound redesign and much much more, while keeping nearly every new feature in the mod totally optional.
This compatibility patch will allow you to play through Research and Development with the revisions gameplay and visuals enhancements that HL2: MMod has to offer.
In chapter 2 "N.E.R.D.S.pt.2" when you use energy cube to against Combine the game will crash because player don't have weapons so i must add crowbar to fix problem. Also if you try use prop to kill headcrab the problem also happen, this problem probably is mmod itself.
I didn't realize that you would want to have the MMod to play R&D.
I would rather look for mods that "polish up" the graphics. The "gunplay" (or rather their lack) is already one of the things that make this mod exceptional, right?