I think that you might be expecting too much of your MMM. You may want to switch to a RFM with a slip clutch if the objects are a concern.
All I'm expecting is that an unforseen obsacle will not destroy the tractor. As I pointed out in an earlier post, a homowner with an immaculate, obstacle-free lawn could turn up a rock or run over a toy or tent stake or baseball bat or whatever. In my experience, the tractor stalls. From what others have said it seems there is some built in slip, but the stalling still worries me.
I have a bigger tractor that I put a box mower on the back of for the heavy stuff, but when I use my swisher offset to get under the branches I like to use the BX at the same time. I can do an 8' swath. We have pick your own apples so the orchards require a finish mow throughout the season.