Re: MM300 clasp on Sumo
Not much of a difference, unless your wrist swells significantly during the day. I know mine can, so a watch I put on in the morning can be quite tight in the afternoon. Otherwise, the MM clasp is significantly bulkier, and you may did yourself catching / scratching it on things which weren't a problem with the regular clasp (both w OS300 & LandMaster 10th). I actually think Citizen's example is much better (from PMX56 family) for exactly that reason, even if it doesn't feel as sturdy.
Then again, if you ensure you have one more pair of holes available on the clasp to extend the strap, all you need is a mechanical pencil to adjust until comfortable again! ;)