I think, flying shields is a bad idea for some reasons:
1) Shields are strong cards and can kill a whole deck. Flying shields makes shields OP.
2) order of shields becomes important:
e.g. Ice Shield, Gravity Shield: Can the >5 health creature be frozen ? Or is the creature blocked by Gravity Shield and then -> no freeze possible.
Diss Shield + Titanium Shield : How many quanta are absorbed ?