Alfine 11 or 8?
8, it's been on a couple of bikes, I like it, but find the range a bit limiting. It's geared lower than it has been previously about 27 - 83", I'll see how that goes. I've been spoilt by the Rohloff!
Difference in comfort or something else? Which fork is better for off-tarmac use?
Yes comfort, though that might be putting it a bit strong, I can certainly feel the road surface more. I swapped wheels to confirm it was the fork rather than anything else. I haven't done any long rides with it, not sure I will, I can't see it being an issue even if I did, and maybe front luggage would dampen it. I choose the 853 fork on my proper Mercury for aesthetics, I had no doubt it was a comfortable fork, and I'm not suggesting the touring fork is uncomfortable, I'm just a little taken back by how noticeable the difference is.
Off road? We're spoilt for choice round here with well surfaced cycle tracks like the one pictured, many of the local roads are rougher than that! I suppose the more robust touring fork might be a better choice if I was expecting to ride anything more adventurous, but then it probably wouldn't be on these bikes.
I do occasionally get caught out of course, this went on for a lot longer than expected, but apart from being slow going wasn't a problem