In reply to Martin W:
> The Ultra Mountain, depending on which size I got, would really only offer me significant adjustability in one direction or the other, not both.
Ditto for me. Someone at BD has made an idiotic design decision as the sizing on the Ultra Mountain FL has so far deterred me from buying a pair.
For that reason I am currently considering the Leki versions - Micro Vario Carbon (comparable to Ultra Mtn FL) and the Tour Stick Vario Carbon (comparable to the Compactor). See
http://uk.leki.com/trekking/f-poles-special
> Can anyone suggest a compelling reason for choosing the Ultra Mountain FL rather than the Compactor?
In a word, No.