I'd like to see something like this added, but also see some issues in terms of play balance. If/when subs are added, something like this would seem to be a necessity. While tincans were indeed operationally grouped into flotillas or squadrons, they did often operate independently on the tactical level. So I think they should be spawn-able from either a fleet or a port, like PTs are. I think there would have to be some sort of limit on the number that could be spawned from a given fleet/port, and within a given time period; simply perking the heck out of them would not be enough to prevent abuse, IMO. Part of the problem of course is in the nature of how it's treated by the code. If it is treated like a single-ship fleet, we can't directly control the helm (speed and direction) as we can with the PT boat. This makes deploying torpedoes from it very difficult at best. If, on the other hand, it is treated in the code like a big PT boat, we get direct control, but don't get auto-ack, and are limited to only one other person gunning with us. I'd prefer the latter choice, if we're assuming we have to live with the current limitations in the code.
On a side note, along with torps, I'd want the option to make smoke, since this was a vital defensive ability of the tincans in surface actions.