Well, keeping an ARS alive in enemy territory is pretty easy because of how hardened it is, so that makes it something of a super-researcher by nature. That's why it was a problem when it could be used outside of supply when the other labs could not -- people abused the heck out of that.
The ARS really has one real function: being captured and granting you a new ship class. The knowledge income it creates is incredibly secondary and just so that it isn't completely pointless after the initial capture. In the past, these things weren't even mobile, but I made them mobile so that they would have some incremental benefit beyond just the ship class thing.
But really, I feel like they already have way enough of a central function, and I'm not looking to make them any more awesome than they already are. It's not like people are not capturing ARSes or feeling like they are lacking in purpose!
When it comes to alternatives to the MkIII stations, I really don't see that as a priority. It's a pretty broad mechanic as it is, and something that simply sets up a new class of encounters. You want to K-raid an enemy planet, it says? Fine, just be prepared to spend the time and resources required, and to build a beachhead. But how you go about doing the beachhead, and what sort of conflict results, is where the variance comes in.
At any rate, that should be uncommon enough not to become monotonous in the first place. And I'm feeling that if there are changes to be made, in terms of adding more variety on knowledge raiding, that should be something that would happen several weeks or months into the future, if it becomes obvious that there is some issue. But I really don't expect such an issue if players are playing in any non-OCD manner (and you sort of reap what you sow if you go completely OCD on the game, same with the 60+ hour games, you know you're in for a grind and that must be the sort of game you're looking for).
EDIT: Well, I'm late to the party on my response, but I typed it out so here it is.
