id go either for another beddy grey or a grey/whippet , imo if you go for your mates deer/grey collie/grey their would be that much different blood and genes that the pups would grow up to be all sizes , all looking different , just because the bitch is 24 and your mates is 25-26 doesnt always mean that the pups will fall somewhere between the two , yes its likely that some will but then u may get 1 that throws more to the deerhound and turns out 28tts or one that turns more to the beddy at 19 tts , at the end of the day mate its your choice ,, ATB LLOYD