Im on the hunt for a realforce as well. Here's a general summary of what I've researched.
55g - noticeable feedback and obviously stiffer, pretty much a perfect fit for anyome accustomed to a IBM model m. But might be too stiff for some, which is why the uniform 45g is sometimes preffered.
87u variable (35g, 45g, 55g) - 35g addresses the issue tthat the 86u had with accidental keypresses on the 30g pinky keys. Excellent for typing and overall provides a better typing experience if you type properly. Not so great for WASD gaming obviously due to variable weights and not that useful for someome like me who doesn't touch type.