I'm asuming you've not purchased the kit yet. But if you had I'd just call them and ask which to use, but I thought they came with the kit.
hmmmm.. you might want to wait 'til the double A arms suspension gets done.
but that aside I don't know of any other companies providing these types of suspension. Frankly I don't know if much other than easy adjustablity is gained. Other than that, if easy adjusting isn't that important, I'd stick with the stock stuff.
But, yea if this will be a total handling machine, wait or even design your own double A arm suspension.
check out
http://www.centralvwaudi.com/Beetproj.htm
and do a search for the post about the double A arms. I've been toying with the idea of using fiero spindles with custom lower a arms and these for uppers.
http://www.polepositionrp.com/MODIFI...ROL%20ARMS.htm
good luck