I dunno, possibly I guess. A 60" MMM for the OP's BX adds what.... $2,000? Commercial ZTR's are around $7,500 and up (I paid $9K for my 60" Ferris). The used commercial ZTR's I found were pretty much spent and they still wanted $3,000+ for them and a used commercial one with hours will be soon be needing repairs while a new MMM should be trouble free for years. With what all I have to mow I was able to justify a new ZTR but if I had a couple acres to mow I'd prefer having only one machine to do it all.
Will my Ferris mow better than a BX? Probably not, a little faster yes but that just means less tractor time!