Fine & dandy all, but is half-a-dozen 100kT Drones better than a 600kT Battlecruiser? Your BC is going to be more versatile, and can be refitted.
I can see the maintenance aspect; but I confess that in most games I play I have an overabundance of material until I start atmosphere conVersions.
At that point I'll normally have a high-speed fleet with a warp-point creator - and a closer - available. Max reaction time: 2-3 moves to any part of the empire, and I'll have closed off some warp points in order to create choke-points.
So I still maintain a surplus. I guess I'll have to play around with Drones to find out if they're worthwhile: I suspect however that if you're down to reliance on Drones defensively you've already got problems.
Mind you, I said I thought Drones were just big, expensive missiles: when they hit they're big, expensive,
effective missiles
Those special warheads look
nasty !