I'll chime in my my opinions regarding leeches and parasites. I didn't read all the posts that were already made, so if someone already mentioned these... well... shucks.
Leeches and parasites.They're too effective at what they do, basically.
You know, the idea that you can shoot with a gun to capture an enemy is just pretty darn cool in itself.
Shooting with hundred guns to capture hundred enemies.. well, it just gets ridiculous.
A blob with leeches/parasites plus an MRS can just roll over just about anything, constantly replenishing its ranks from the AI. You could say that by building a parasite, you get one or more ships for free if you use 'em right. Even more so with leeches. You shoot once with it, and in a potentially good situation get, what, 20 ships for free?
Yeah, I know 'free' is a relative term, since repairing the captured stuff costs resources 'n so forth, but that's quite beside the point. It's not the cost that's off, it's the ability to procure stuff so easily and quickly, and at the same time causing equally many losses to the enemy. You have guns that do a factory's work for you, basically. Things like that should be special. Like "Hells yeah, I managed to capture a ship from the AI!!11", not rolling over enemies with a blob and pondering why the fleet doubled in size suddenly. Well, maybe not THAT inefficient, but I'm sure you get the point I'm trying to convey. Placing limitations isn't really the way to go here once again, I think. You should be free to capture high Mk things if you want to. It just should be harder and/or slower than it currently is.
I'm not really sure how that could be achieved, but I'd start looking at the rate of fire/captures and things such as the leech's ability to mark multiple things at once. Too quick, too easy, too many successful reclaims in too short time.
I know people who like reclaimers will definitely throw a fit over the idea of weakening these, but this is a special feature unit and needs special attention. Weapons and ability to reclaim are hard to balance altogether, since they are not directly comparable. Reclaiming produces ships, weapons destroy ships.
Wasn't there also talk at some point about nerfing MRS's? For instance, if they couldn't be brought to battle as easily as they currently can, and maybe if reclaimed ships started with full engine damage and couldn't move or somesuch, then running over everything with a Reclaimablob(tm) wouldn't result in the captured ships becoming so battle-ready right away. You'd need to pay much more attention to successfully capture stuff. Then again, sounds like adding more microing, which isn't necessarily good either.
Aye... problematic. But as it is leeches and parasites can do a Factory's work for you very efficiently in many situations. And not just Mk4. Actually, you're better off not building full caps of any commonly available shiptype, so that you have space for captured ships. Better save the resources for something else than building ships from Factories and forfeiting the captured stuff because caps are full.
Did I repeat myself there somewhere? I think I'll stop here before I do.