HTupolev

Worst-case chainline difference between double and triple, assuming that the triple is well-designed, is a few millimeters. Not a particularly big deal.

I think the biggest problem with modern triples is that they've been bludgeoned by poor design practices, unfortunately.
Quality triples paired with six-speed freewheels routinely had q-factors in the low 140s. Allowing for the outer cog being a few millimeters farther outboard on 11-speed, a 3x11 triple would reasonably be expected to be in the upper 140s. But - perhaps thanks to the lack of permutations permissible in two-piece cranks - the drivetrain manufacturers play it safe, and then add a bunch of room on the NDS to keep things symmetric (which is silly and pointless). So instead, modern road triples usually have q-factors in the 160mm ballpark. Absolutely bonkers.

Pretty much any modern well-designed crank shifts smoothly and consistently every time. Since triples usually have smaller jumps than doubles, they typically shift snappier and need less compensatory double-shifting than doubles.

Although, my view on this issue is probably colored by my tendency to throw a friction shifter at every problem. I don't presently have any triple cranks in my stable with a brifter-actuated front derailleur.