@Alex: a lot of the limiting factor in my experience was getting between fights counting against them in any battle worth deploying them in. 180 seconds + CR degrade time of combat is acceptable for such a mobile damage dealing platform. Their utility in being of any benefit to the rest of your fleet is still missing, of course, but if you just want to kill things dead and don't need support for your piloted vessel of choice, they feel okay.
A different matter is how expensive I think they are for what you get out of them, but that's balance tweaking and something to be looked at once you've gotten the important matters out of the way - like entire game mechanics such as Economy. Once you do get around to it however, I feel that for the campaign play these should be fearsome monsters that are rarely seen deployed in combat - an Abrams M1A1 intervening in the squabbles of T-55, T-62, and T-72s - Ruinously expensive, but utterly superior to everything else.