Nope, this is just one of the overpriced ones.
Yeah, it kinda is. The RX-78 has a full set of hand options, better part separation, more than two weapons, and only costs $10 at retail...
Even the Gyan Revive practically matches that, outside of the fact that it only has one extra hand and two accessories.
Ehh, depends on the suit. Some IBO HGs are great (namely any iteration of the Graze, except the Reginlaze), but many are really just not well engineered (original Barbatos and Vidar have awful stickers, both versions of the Gusion Rebake have almost no color separation, etc).
Overall, the 1/100 line is a much safer bet. They aren't just larger toys, they're still improved, even if not MGs. Honestly, I can't really imagine there being many differences between one of the 1/100s and an MG IBO kit. The engineering is mostly up to par.