I have tried Anik alfalfa, and love it. We seeded it in some absolute blowsand that had a pH of 4.8, and organic matter levels around 0.5%. It caught, and with careful grazing and long rests for the first 2 years, it is highly productive in a stand with another variety of alfalfa and some meadow brome. The stand is now 6 years old and more productive than ever. It's not a heavy yielding hay variety due its small, fine stems and leaves, but is excellent for grazing. Responds well, and is extremely hardy, very tolerant of grazing and/or winters.
Seed came from Peter Lundgard at Grimshaw in the Peace Country of Alberta. He's a good friend of mine and sells alfalfa seed and cutter bees all over Western Canada. If anyone wants his number just msg me.
In sandy soil you almost always have a low pH, so clovers don't do well usually. We've had good luck establishing alfalfas and milkvetch through mineral, although it's patchy at best, which is to be expected. I like doing it in patches of buckbrush, silver willow, leafy sphurge or any other "undesirable", so you can get something competitve there working for you. The hoof action, manure and urine in those concentrated areas always helps with establishment of course.
I've posted pics before of the alfalfa/meadow brome stands we established in the sandy field, and it all had Anik alfalfa in it.