Answering this would potentially reveal too much information. But let me try. Raks are actually the worst offender and the most difficult to balance because they can possibly spawn more. Other figures are much easier. For example the Sith Mutant is easy to handle.

Now as for the possibility of SA 3,4,5,6 it becomes trickier. We would likely use the precedent of all unleashed force powers that scaling them also comes with changing between "replaces attacks" and "replaces turn". Making it "replaces turn" adds a very serious impediment to any ability. That's one way you do it. Making it a save is a very bad idea. No one is ever going to spend 5-6 force points on something that still requires a save, even a save of like 6. So odds are, the way you balance it, is by making V-set pieces for the piece you can bring in with SA. Let me give you an example.

Let's say we made a Clone Emperor who could use SA6 which does 60 dmg, replaces turn, and brings in a Chrysalis Beast. We then might make the CB with a lower amount of hps and a lower cost to balance the two together. Obviously bringing in something like a full health rancor is pretty wrong for the game. So anything above SA2 will need carefully balanced and play tested figures with the ability in mind. Of course they also have to be balanced for play as a figure themselves, which is why you make new figures, not try to fit in old ones that were never created for such a thing as SA. In my book, there are only two figures that WotC made that work as is for SA, the Sith Mutant, and the Rakghoul. And of the two, the Rak is by far the more abusive figure. Hence the reason we began with the Rak and SA2 in figuring out how to balance this stuff.

My final thought on it, is this. We were careful not to box ourselves in a corner with this one. We have a number of ways to adjust the scaling for balance as we go forward. For example, the SA6 I made up above, could be changed to figures with 40hps remaining, have a range of 2, and replace attacks. We are not boxed into the corner that a couple of people seem to think we are with future versions. And also to say, we have no obligation to make multiple versions. I'd like to myself, but I am not the only designer. And we aren't going to be handing this out to 4-5 minis in every faction. It will be fairly rare for the most part, restricted to those characters that actually did Alchemy, and even then, not all of those will get it - probably depends on if that's part of that character that we want to represent. We may well never go beyond SA2.

With that all said, I talked about this on the SHNN the other night, you should listen if you haven't already. We do have a tentative plan in mind that we worked through when making SA2 so that as we move forward if we have minis that we want these things on, we know roughly how to begin as based on the SA2 precedent. Design is a very forward thinking process, something that I think the average player really fails to grasp when they make complaints. Players tend to look back, where as designers really have to look forward. And because we can't often share our forward thinking ideas, players get stuck in the, "Well I see no solution so there must not possibly be one" when in reality, odds are the designers already thought of the issue before you brought it up, and already have a tentative plan for how to work with it in the future. As I said on the show, other than a couple of very minor interactions, there has been literally nothing that has been brought up by players after our releases that caught us by surprise. Every issue of concern or complaint has been something we often talked about in our private forums. Obviously you can't know that.

This is to answer creme_brule's earlier post, did not want to quote it because it is to long lol.
Anyways, comparing lord vader to mace windu is not a great comparison because yeah vader can do 160 with thrawn but that is a huge amount of points where as mace windu's damage output is not reliant on having anyone else in your squad, the other issue is that it is relatively easy to force absorb/force cancel vader's ability to even do that much damage, especially with some of the newer usable pieces coming out with those abilities. Same goes for mara jade, jedi yes she can do 120 if you are not activated, and if she gets to use lightsaber assault. Mace windu on the other hand has to roll a certain number, while this may appear like luck has a huge affect on mace windu's damage output chances are that he will be doing just as much as these other characters because their ability to do damage is quickly becoming easier and easier to counter, whereas mace's damage just happens.