I had my B2601 for 250 hours (about a year), I have not noticed any significant difference in burn between the two. My anecdotal hunch is the 3310 could be a little more efficient, but those efficiencies are lost during regen so it ends up a wash.
I know when I brush hogged or tilled most of the day with the B2601 it would take about 5 gallons, the LX3310 is the same.
@S-G-R you have been working your new 3310 recently, have you noticed a burn difference between it and your prior LX2610?
I would not let emissions deter away from the lx3310. It has a warranty, and comparing it to a system that uses DPF & DEF like the aforementioned F-350 is apples to oranges. It only has DPF, and its operation is entirely in the background.