bird i can see why your going down that path but that cross has some of the bad points your collie cross has,yes it should have better drive and more bottle but the things that niggle you with bryn can play a part with that breeding as well,heat stress is almost a certainty there coats are very thick,they can be temperamental sulky,some come very heavy and because of that are limited.
having said all that,that may well not be the case but i am sure you wont find one as dexterous and nimble in the field as brynn.
ive had experience with ally crosses and out crosses and can say those were very