I really want to like Guardian Owl, but he’s just so painfully slow. If E&P tweaks his speed, he could be a lot of fun.
Also, if they ever allow for different defensive configurations, he could be viable. A configuration that put two tanks up front and three defenders in the back–as opposed to the 3-2-1 formation they allow now–could make Owl much more interesting, as attackers could be tempted to take out the faster tank and take their chances that they can kill Owl before he goes off; but if their timing is off, Owl can really do a lot of damage. Another great strategy for Owl could be, if we were able to run one (initially unassailable) defender in the back, two on the far flanks, and two tanks up front in the middle, hiding Owl in that back slot could make him really interesting, too.
I’d love to see E&P allow for variations in formatting, and I’ve posted about in the suggestions forum before, but outside of that or some further tinkering with Owl’s abilities, no. He’s not worth leveling.
But don’t feed him. You never know what may change in the future.