That said, if you're going to put him on anyone, why not put him on Dutch?

That was not competitive in the past when wave 1 was new. Nothing changed.

Make it a BTL-A4 and you've got potentially 3 TL's to pass to allies.

Now that is an idea. Might be worth trying.

Compare poor R5-K6 to R4 Agromech. Now imagine if R4 required you to roll that evade dice before you got the T/L. Would anyone like it? R5-K6 is BARELY usable on Dutch, and thats his best (only) realistic platform to use it on. I used the hell out of a 3 ship rebel list with Corran, Dutch, and a Gold when i first started, and after awhile i swapped R5-K6 for R7-T1 and got much better mileage out of him.

I chuckle when i see someone complain about how Rebels get all the cool Astromechs, when they really mean Rebels get Shield bot(R2-D2), stress bot (R3-A2),and i-have-1-or-2-pts-left-over-oh-here's-a-pt-sink bot (R2). The rest are just range from godawful (R4-D6) to very niche and occasionally useful (R7-T1, R7)

Both of the Wave 1 R5 droids suffer from the problem of Green Dice (and D8 also costs you your action). For the cards to be worth using at all would require something that allowed you to ignore this inhibitor.

R5-D8 however can discard damage and it has better odds than the free target lock. However it pales in comparison to R2-D2 which guarantees a shield with every green move.