From an emailed response posted to Baen's Bar BuShips dated August 17, 2004:

How big is a recon drone?

    Just how big is a drone? Or is that classified information? Obviously, the size of the drone (assuming that the CMs proposed above would have to be drone-sized) is going to affect how reasonable it would be to think in terms of deploying them through missile tubes.

     

    To give you an idea, the standard Manticoran counter-missile as of War of Honor, masses about 12.5 tons. Havenite counter-missiles are about 25% larger, and individually less capable despite their greater size. A single-drive capital ship missile runs to about 135 tons, or better than ten times the size of a single counter-missile. The remote platforms being deployed by the RMN these days, which would approximate the minimum size capable of squeezing in the proposed drive arrangement, are over twice the size of an old-style capital missile, which is why they are deployed by swimming them out of boat bays rather than firing them through tubes. So, let's assume that you could build one of these things for "only" 270 tons. In that case, each of them would replace something like 22 standard counter-missiles. Not a good trade in the opinion of the missile defense officers.