Your original post asked "what are your thoughts on a fowler versus a rifle" and that is what I was replying to. To elaborate on that question, I think that if you want primarily a shotgun with some utility as a short range deer gun then by all means get a fowler. If deer hunting is your primary interest you will be much better served with a rifle. There are no shots too close for a rifle but plenty too far for a smoothbore. That answer would be the same whether we were talking flintlocks or breechloaders. If that's not the answer you wanted to hear, I'm sorry but that IS the question you asked.
We all draw the line as to "how primitive" we choose to go. I have hunted the Colorado muzzleloading season since '71 and hunting with a traditional sidelock rifle, flint or percussion, with patched round ball is primitive enough for me, I see no reason to further handicap myself by trying to make do with a smoothbore.
For the past three muzzleloading seasons I have been camping with five people and all together we have taken nine elk, only two of which might have been in range of a smoothbore. Again, there is quite a difference between 50 and 100 yards.