Well you've got the pin deck height adjustment on the Bob-Cat vs Dial on the Gravely. Faster reported blade tip speed for the Bob-Cat, 18,142 vs 17,000 FPM. A bit odd that Gravely has the same blade tip speed of 17,000 FPM listed for all deck sizes 42, 52 and 60. Usually they differ. I don't know what the hour meter is on the Gravely but I think the Bob-Cat has the digital one with the maintenance reminder function. Nice feature. Hard to tell from pictures but is the deck suspension system on the Gravely beefier? The Gravely "features" show an 11 gauge deck vs 10 gauge for the Bob-Cat but the spec sheet for the Gravely says 10 gauge. Not sure which it really is but the 10 would be preferable.
Also Bob-Cat has gone to Zero-T brand rear tires on their machines. It looks like Gravely has the Carlisle Turfmasters on it.
The bolt-on tow hitch for my Bob-Cat was $10. I'd guess it's an option for yours, even if it's not listed as an accessory (it's not listed as one for my model on the website either).
One thing I will say about my Bob-Cat Fast-Cat Pro is that after a season of commercial use, the only problem I've had was it throwing the deck belt off once when I engaged the blades and that seems to have been a fluke. Not a single lose nut or bolt or leak or other issue...they seem to assemble them well. Whether that translates to the CRZ I don't know.
The CRZ has the same style deck as my machine with the double-wave baffles. It's pretty highly baffled so clippings come out pretty small and it cuts well but the double baffles in the front of the deck do accumulate crud. They got rid of them on the newer top-of-the line machines. It also doesn't handle wet grass all that great, it tends to discharge wet grass in fits and spurts rather than continuously. Also, my dealer sets the deck up so that the front is actually higher than the rear. They said that they get complaints of stringers being left if they pitch them with the front lower and customers were complaining that they had to double cut everything. Usually the front is set up lower than the rear. Setting the rear lower actually causes each blade to be cut twice but draws more power.
