My only experence with shell was with two pair of Alden (Color 8 + Ravello). As far as comfort, I didn't find shell any more comfortable than calf. Second, the first day that I owned my Alden PTB in color 8 I was walking out of the shop to my car, there was a light rain - I didn't think much of it but later that night I noticed "bumps" all over the top of the toe (both shoes) - no matter what I did those bumps remained for as long as I owned the shoes. The same with scratches - I could never get rid of them or even minimize them (and I used all the best stuff, with the Mac Method). Then there were the creases - I have never had a leather that creased so much! I have had boots and chukkas that I wore in all kinds of weather that had almost had zero creasing. And I could always, with a little boot oil, Obenauf's, or Saphir make calf skin look new. Once there was a real blemish with shell you had to live with it. I was told that this all was "character" - sorry I didn't care for this "character." But it really comes down to personal preference, and at 60 I guess I'm just more at home with calfskin. It is what I used and cared for most of my life. I know calf, I like calf.