I would be curious to read a comparison between M5 and MHG, since I have never been able to try a pair of them.
Anyway, my two cents. I had both M5s and M7s for a couple of weeks before I decided to keep the latter. I really liked the M5s and certainly could live with their narrow fov, but once you get used to the vast, immersive view of the M7s it is hard to go back. Not only from an enjoyment point of view, but also from a practical point of view. The M7s also seemed to me to have greater transparency, especially in low light conditions. The only drawback I found was in the ocular accommodation, perhaps because of the size of eyepieces and eyecups: the fact is that, while the M7 is more than usable, the M5s fit the shape of my face better. Other than that, if you can pay about $100 or less more, I think the M7s are worth it all.