E boats would be a big step up, however I question if enough users would ever partake to truly make it worth the dev's time?
Also Eboats should be shore based not Task Group Based like our current PT.
Last I think the biggest problem with any kind of boat, sub, ship, in Aces High is going to be the time factor.
In SH3,4 etc you have a time compression you can use to turn that 3 week cruise to get into position into 20 min or so of in game time. In AH everything is live all the time, and needs to stay that way.
So who is going to spend 4 hours of time getting their Eboat into patrol area? Not counting the time they actually spend patrolling. Only to have some plane drop a bomb on them and send them back to the tower after ???? hours trying to accomplish something.
Its not that many of us wouldn't love to see it, including HT himself.
Its trying to figure out a way to do it that doesn't totally break immersion without breaking something else.