I had to modify a few impliments for mine over the years. I'd say modifying the standard QH to fit non-standard impliments is the wrong way to go. Modifying the non-standard impliments is going to be the better longterm solution.
I the QH on the Ls I've had. The extra length & associated capacity decreases may be harder to swallow on a B or BX. I've had a few PTO shafts rub on the QH. The PHD I modified to fit on my QH (required a hydraulic toplink) had the shaft bent several inches several times.
I thought it was easier to make the cheap QH wider than making a rototiller, mower and snowblower narrower!