I know [I think] what you mean about having a 'big looking' dog - I didn't want a fierce dog just one to look the part.  My Elkhound does this, Yet she is the softest Teddy Bear ever.  I have had lots of trouble with kids/youths on my estate and the 'naughty' ones are put off, even scared of her.  What they don't realise is that she wants to play with them.  I have trouble walking her as so many of the local kids know her so well and come to say 'HI'
She can be a couch potatoe or hike for miles or whatever activity..
She moults - PROFUSELY - but only twice a year. This is great fun, apart from wearing black work/going out clothes, for the 2-4weeks her moult lasts.  After that, barely any hairs, certainly much less per month than my BC per week!
Elkhounds bark - but certainly nowhere near as much as many other dogs round here - despite the barking of many other dogs round here.
I had your concerns over sheep chasing.  Amazingly she is much better than my BC [and others before].  She loved our rabbits [now sadly departed] and used to sit like a sheepdog at their pen gate whilst I cleaned them out, they had a hutch enclosed in a rather large run/pen, to stop them getting out.  she was also rather fond off 'helping' clean the pen out [rabbit pooh mmm..  lovely]