Apologies for barging in on your thread.
I'm not a big fan of universals - they all have an inherent problem, I think.
If you cut a corner too tight and collect a board, look what is likely to happen to the wheel.
If the wheel digs in to the board and the upright separates from the balls. it may well end up at 90º to the chassis for an instant. If the universal comes out of the outdrive, you may just get away with it, but even then the shaft is flailing around and still attached to the wheel. A dogbone in this situation will just fall out of the outdrive and the wheel.
A decent bumper helps decrease the chances of the wheel digging deeply into the board on an impact - that's the primary cause, I think. Maybe a bit more end play at the outdrive would help.
While universals are more efficient, we have gone back to dogbones for reliability reasons - not to mention the financial angle.
Just my 2cents worth.