Thanks mate.
Here are my thoughts on those MGs:
G Gundam - very basic but still a fun build, the only gripe I had was the little screws. I did however love the rubber parts used for the base of his feet since they're ultra grippy allowing him to be posed in various action stances and not topple over.
Epyon - this guy is a totally awesome build, the engineering and design is well thought out - I especially love his chain/shield weapon that can be extended and flex or kept straight simply by pulling out on each of the links. I highly recommend it if you haven't already got him.
F91 Harrison - I found him very fiddly and my patience was tested since he's quite small for a 1/100 MG (meaning the parts were all relatively smaller too).
Shin Musha MkII - a very enjoyable build and looks the goods once completed, but I hated the gold parts since I needed to pay extra attention when trimming them (since the gold cracks and flakes if not done properly)
As for RGs, I don't really like any of the ones released (so far), but the thought of an MG type build in a smaller scale doesn't really appeal to me since I'm predicting it to be quite fiddly (like the MG F91).
I intend on jumping on a PG in the not too distant future - just haven't decided on which one yet (plus I still have a ton of MGs and HGs to work through first).