I have a rack of 7 A12's that I built and as much as I hate to disappoint you I LOVE them and have nothing bad to say about them at all..... well other than I am thinking of picking up a N72 or something to fill out the rack and I have to take the whole thing apart to get it in there. I am not looking forward to that.
Yes I would consider them to be high end all the way, don't be fooled by price.
I have never used the A12's and say a 512 side by side but from what I remember of the 512s the A12's have
that sound if you know what I mean. Michael W. did do a side by side on the API and the SCA and he picked the SCA, that says something (but only because he thinks his older APIs might need some work, other than that I get the idea he thinks they were very close in sound).
I would be surprised if you are not very happy with anything from SCA. And don't let anyone fool you, 9 out of 10 cats here could not tell the difference between the real API and the SCA inside a mix or even soloed so you are getting pretty close to the "API" sound for sure.
Hope this helps.