Here's an example I've been working on. The double stops on 8 I'm generally hitting the G & B string with my 1st finger laid across the 2 strings. For double stops on 10 I'm laying my 3rd finger across the 2 strings. For the 11/12 double stop (which sometimes I slide into) I am using my 1st and 2nd finger.
The 3rd finger laid across the 2 strings is the hardest to keep clean. At least when moving up the neck I can do the double stop at fret 10 with my first finger, but it feels more natural to do it with the 3rd finger on the way down. If I try to play the whole thing with 2 fingers it seems like it can get a little hard to cram them both in there for a clean note on the 10th fret as I can't get both fingers down right next to the fret.
Just an example there are a couple of others that seem harder to modify to use two fingers. This one is moveable, this example is playing over a C chord, say I was going to play it on an F chord it'd move up to the first fret. On my acoustic guitar the effort to fret the double stops is way lower on the first fret but the stretch is harder. When I play this stuff on my Telecaster the fretting effort is pretty effortless anywhere on the neck but the stretch is quite a bit harder up at the first fret due to the longer scale. (I have a Taylor GC with the shorter scale.)
I may be I still need to investigate some more setup advice. There is a complex relationship here for me where I have to fret the notes harder to hit the strings harder without buzzing to get good tone when I'm this far up the neck. The hammered notes (grace notes) are particularly challenging up the neck compared to closer to the headstock. That's in contrast to electric guitar where there is seemingly no drop off in volume as I go up the neck so I can hit the strings more gently, and then not need to fret as hard to avoid buzzing.
Tempo is nothing outrageous here.. 80-100bpm for quarter notes but these are 8th notes.
Code:
e----------------------------------------
B---8----10--11--10--8----10--8----------
G---8h9--10--12--10--8h9--10--8h9--------
D----------------------------------------
A----------------------------------------
E----------------------------------------