The FSA looks more or less exactly like the Ultegra double. I've got both spindles so if the one doesn't sort out I'll try the other.

I was wondering more generally about the purpose of the deeper back cages on the triples… is it just extra capacity or is there some other advantage?

Started poking around the V-O blog site and came across this little bit, where he says the deeper cages helps them upshift from small grannies.