If you have ever seen one of these things hooked up you would not be concerned. You point out that the toothbar is bolted on...yes, to a 12 gauge bucket side held by a couple of bolts that would rip through in no time if you routinely snagged rock edges while backing up. I have a RR (and have had toothbars etc) and really there is no siginificant danger of the thing falling off. If you are really so concerned it would not be hard to modify it to be essentially like a toothbar simply by welding on a tongue on each side to bolt into the bucket. IMO that would be less secure however. The other point is that it only takes a couple of minutes to mount or dismount the RR while if it was bolted like a toothbar you are pretty much stuck with it while in the field. Not hard to take on and off as tasks change while in the field with the factory mount system.
Yes, I gathered that you've got an RR, IT,...
; I hope they give you a commission.
In point of fact I beefed my bucket with 3" bar stock welded on to support my toothbar bolt-in and to support the upper edge mounted grapple. Even so what helps the toothbar most are the teeth that hook the cutting edge.
Really, I put the brushhog into very thick tangles that over the year grow to be easily 12' deep and as high. Aside the brambles there are usually broken branches and other winter debri that comes down from the hills behind me and sometimes get my brushhog so tangled into that stuff that I can't pull it back up without shutting down the cutter and lifting it. Even then it usually brings a ball of stuff that's near as large as my little tractor.
But note that I don't even venture into that stuff going forward - the RR wouldn't do my brushcutter any good.
There ARE other parts of my place where the RR may have uses so I AM now considering it, OK?