Why would you compare it to the speed of the drone? It's not like the drones are trying to chase down targets, and the Grav effect is supposed to help do that.
Have you tried the Kite Flier AI yet? How about a double Kite Flier/Speed Racer AI? Anything that slows ships, be it grav effects or engine damage are a big help with that kind of opponent.
I'm not sure whether you're suggesting it's too weak and should have the gravity effect buffed, or it's useless and should have its gravity effect removed. I'd strongly argue against the latter.
I haven't tried Kite Flier/Speed Racer yet - and that does sound "phun" - but I played through a game against a normal Kite Flier.
Kite Flier has some issues right now with drones in general. For example, if they target the drones, they end up running to the max distance the drones can reach - too far away to do anything to your real ships. I had a single Mk I enclave hold off about 100 missile frigates on one of my worlds for several minutes, because the attackers kept running away from the drones. But if they target your other ships, then the drones get free reign to kill the 'kiters'.
And without the Speed Racer, the kiting and the Grav drones basically don't impact each other. Right now, the Mk I Grav Drones have no impact on about 80% of units. A Mk I or Mk II sets the max speed to faster than the Drone's speed anyway, so it still could be kited. And if the ability isn't useful at all until Mk III, it needs to have a look taken at it.
So, I think the Grav effect should either be upped, so it has an impact, or replaced with something else (which would be sad, since I like the idea of Human-controlled Grav Drones like the AI gets).