I don’t honestly know enough about mining to comment accurately here. However the many threads over the years about Orca’s and Rorquals have had pretty convincing arguments and data to show the Rorq is clearly OP and the Orca nearly so. But at least the Orca seems to have an interesting variety of uses so that may justify its stats.
The T2 versions of the Venture rarely get picked on as OP or unbalancing. I hear about more uses of the Prospect for its’ cloak than the Endurance for it’s extra hold, but they both seem to get some use and not too much abuse.
As others have mentioned, this leaves the Porpoise as the ship that could use a new version. I don’t see a lot of discussion about Porpoise’s and I confess I liked the idea of it when it was first announced (mostly just because I liked the idea of a ‘Space Flipper’ ) and was a little disappointed it didn’t turn out to be ‘cooler’.
So maybe a Porpoise upgrade could be devised that would be cool but not OP. Not sure what features it would need, myself. Covert cloak? Larger fleet bay? A special module that slows it down and fills the fleet bay but allows it to compress ore? A special ability that allows it to project a “warp enabling bubble” so it can sacrifice itself on the field but allow all the ships it boosts to warp out?
No firm ideas here, just the thought that it needs a ‘cool function’ that gives it more uses than just “a good mining booster for dangerous space” because honestly, how many people even bother to set up mining fleets with boosts in ‘dangerous space’?