Our two Tollers are great flushers. One is not much of a "retriever" tho' so she stays at home. The boy is pretty decent so he comes with me if I'm just heading out for a walk in the woods. It's surprising how many more grouse the dogs see ( and flush ) than I do if I'm dogless. If just road hunting then as 835 says, don't bother with the dogs but if out for a stroll, go for it.
Re weapon of grouse destruction we've found a 20 gauge to be the most versatile if just out birding at the time. If the grouse are sitting, a decent 22 is great but hitting the head of a grouse in flight requires a shotgun. My Son loves the single shot HMR17 I gave him last year for the sitting grouse but better be a head shot or it's just beaks and feathers left.