My thoughts on current balance

[TechSY730]

I think simply not allowing jumpships on HWs would go a long way, though I think disallowing them from transporting any starship would be too much of a nerf. Champions, on the other hand...

That would make Mk. IV and Mk. V jumpships indistinguishable, except for slightly more durability. That, and in certain map layouts, this could wall off the jumpship from a potentially good chunk of the map until you take out a homeworld or two.

An asteroid-level adustment is probably also in order (mkI at xampite, mkIV or only one mkV from titanite).

I can get behind that. Something like that was done for the martyrs (and in fact, the Mk. I martyr was made non-buildable; there is no valid way to get a Mk. I martyr right now)

[Faulty Logic]

Hmm, what if jumpships were not allowed on any planet higher than their mark? So:

mkI jumpships are for internal redeployment only.
mkII jumpships can get around pretty well, but are often restricted.
And so on, with the HWs only accessible to mkV jumpships.

(all human-controlled planets are treated as mkI).

This also gives incentives to actually build the higher-mark jumpships.

Edit: chokepointing problems.... I don't think it would be that bad for most maps. (stuff like maze, snake, tree, ect. are out of luck, but I don't see a problem with one specific type of Spirecraft having it's effectiveness determined by the map, especially as the relative power of other spirecraft (attritioners, for example, are much better at single chokepoint setups) should increase.)

[LaughingThesaurus]

That would also possibly force higher AI Progress, if you're accustomed to neutering a whole lot of planets. You could be boxed in by some undesirable mark III/IV planets and you couldn't get a reasonable level jumpship anywhere from inside without actually taking those planets, or... well... jumping past them.
Whether or not that would be a good thing is up to better players to decide, but I'd suggest attrition per jump to a planet of higher mark. Maybe something like 20% per mark above (IE, if a mark I enters a mark V planet, it would take 80% of its health in damage in that one hop. mark II planet? Only 20%)... or just a flat 35%?

[chemical_art]

You can decrease the number of units you get from an asteroid, which would help, but it still doesn't prevent the idea of saving your transports to just assaulting the ai homeworlds.

Not allowing the cloak ships onto homeworlds completely destroys the V, and to an lesser extent the IV (since you nerf them too for non super games if you want to prevent them from getting your raiding force to the ai doorstep.

You can increase the cost of attrition, but that will only make the hw raids more difficult, not impossible, and increase the micro further of giving custom orders to the jumpships to by avoid IV worlds till they hit the core worlds.

Not allowing jumpships to enter higher level worlds has some merrit, but hits certain maps very hard while leaving other maps with little change (except you will need III jumpships instead of II).

Having the ai core worlds give periodic tachyon blankening on detecting of cloaked ships would cover these problems somewhat. If the transports are alone they will be sniffed out quickly. Combining this with a delay in which a cloaker must be stationary could make it tricky, and on higher difficulties if the ai sends "tachyon emp" missile hybrids that stun cloaked targets for 10 seconds, suddenly lone strikes become triply dicey.