my last bullx 1 /4 bull 3/4 grey, was good on fox, but good on rabbits as well,didnt crunch them. I would give your colliex a good go 1st, then have a think about it, as i said it can be hard getting enough proper work for 2 dogs
I"d agree with this my old dog greyhound/colliegreyhound x saluki took plenty of stuff that bit back but was soft mouthed on rabbits never crunched them and all where returned live to hand