Advice needed on what to do with EW shards

Hey guys, i'm using aircraft, all heroes EW30, Carlie EW 24, and i also have Murphy EW10. Currently i have enough shards to upgrade Carlie to EW29 or Murphy EW21. Not sure if switching to 4+1 is still worth it, or should I go all the way to EW30 for Carlie?

Reasons being:

1. No more 4+1 tactic card.
2. DVA awakening will lose 1 stack if remove Carlie.
3. Did not train much research for Tank.

Any advise is greatly appreciated Thanx!