On a related note:
The way I see Champions is that they are 'Battleships' while normal units are 'swarms of fighters'.
A champion should be a massive (or just really strong) unit that can take a lot of punishment without losing a lot of power/utility during the course of combat. During combat it could be weakened and captures (knocked out and taken captive) or have it's engines/weapons disabled (just knocked out). After combat you would repair it, and get it back ready for another engagement.
A swarm of fighters is far less valuable, they attack in droves (just like squadrons of units), deal damage individually, and can get taken out one by one - making the squadron weaker pretty fast. After combat the squadron can get replenished with new fighters, and different squadrons can be combined to form a new one.