I have a Digital 6 and not ever had the 6AL. The digital has a rev limiter built in, but I doubt there's much else that is significantly better for performance, unless maybe running high rpms.
One other thing to consider is like the pertronix, Crane Cams offers something similar that has a built in rev limiter that is only $64. I used it on my last car, and it worked like a charm after my Pertronix died mysteriously.
http://store.summitracing.com/defaul...arch&Ntt=crane