yes this discussion is back and forth between gear heads, but what I see as positive is for the fellow who asked the question to get more insight into gearing. His question shows he is learning about touring, hence his question, so this sort of question is great to hopefully encourage him or her to look into the details of gearing more.
my experience of using a 50/40/24 for many years taught me (as I mentioned) that having 21.5 g.i. compared to 25 made a big difference. My current mtn bike with a 19.5 is even better for real steep stuff too.
Also doing the shifts from 40 to 24 certainly showed me that I prefer a 10 or so tooth difference between chainrings. I rode that bike for years, with downtube shifters and while I could do the multiple shifts well with two fingers, when I started riding bikes with 50/39/30 or 42/32/22 it was nice with the transitions being easier.
I would have to say that this is the big reason I would be hesitant to go back to big shifts between chainrings (again, depends on the terrain and how much load on the bike that will affect how much easier a double with a big tooth diff between chainrings is going to be, or not)
Im not sure if I am clear here, but I much prefer the smoother transitions between chainrings with smaller jumps--but again, you ride your ride and use what works for you. Its not a competition here, we are out there to have fun.
Last edited by djb; 02-15-13 at 10:22 AM.