i’ve got 150mm dual position 51mm offset having moved form 46mm offset 140mm revs. I don’t use the dual position functionality as I thought I would. My bike (Transition Covert 29) does get light the front on steep climbs but i’ve adjusted to that so now don’t bother dropping the travel. So i’d just go for the solo air’s if I were you.
Definitely go for the 51mm offset. Feels much more lively and manoeuvrable than the 46mm. The only downside is the steering can be a bit more flip-floppy on steep climbs. What I mean by that is as you’re climbing and turning the bars the bars are trying to self-centre – however there comes a point as you put on more and more lock, say on a steep climbing switchback, where they flip from wanting to self centre to go full lock. Again, not a problem, something you easily get used to.
Other than that they are a great fork, much better than the Revs I came from (a basic model of the revs) – no real downsides, only upsides.