I am toying with PBTA as the core roleplay side. Oddly enough, its 2d6 like BT wargame is. And so if I am clever I can make Gunnery and Piloting skill values inform the PBTA roleplay side "success with complication" thresholds. I would need to go over the min and max values the wargame had, and see where those thresholds are for PBTA. Then , well, supposedly the rules would be fair and balanced no matter how you made your character.
Hmm, taking a standard, say piloting roll of 5+ being a clean/full success (83.3% success), and flipping it around to figure out the plus to make it a PbtA 10+, would yield a modifier of +5. Higher than most PbtA modifiers, but then BT doesn't have partial success, so making that a +3 or so would fit in line with your "well competent capability" rolls in PbtA. (A +3 gives at least a partial success 91.7% of the time, and a clean success 58.3% of the time.) Might fit in quite well indeed! And a bunch of playbooks each with special abilities could make for a fun RPG experience that distinguishes even the 'mech portion of the game from standard BT play.
(As an aside, I've really been digging Legends in the Mist for how it uses the PbtA base in a neat new way. No skills/attributes/etc, but instead a series of thematic list of tags where each tag that applies is a +1 to the roll. Very different than standard BT with skills, but could work if there was player buy-in.)
So the question then would be how could 7-9 work on the BT battlefield? Easy might be 10+ is full weapon damage, 7-9 is partial damage? (Half damage for direct fire weapons, -4 to cluster chart for missiles/etc? Something like that?) Does run the risk of having BT battles take even longer than they do now... so flip it? 7-9 is full damage, 10+ does bonus damage?
Alternately could do the more standard RPG side of things, where 7-9 does full damage but brings in some complication. Might be tough to adequately come up with continual complications, though, as you'll do a lot more rolling than during the out-of-'mech portion of the game.
(And for all I know, Destiny maybe already works this way? I haven't had a chance to do a good read through of it yet. Heck, this is quickly written while I'm supposed to be working. Shhhh, don't tell anyone.)