I have 4 acres of Whitetail Institute Alfa Rack that we cut 3 or 4 times a year for hay. My experience has been that the alfalfa in the mix tends to mature(flower) and then lay over on the ground within a week or so. The problem with this is that you have to run your mower down close to the dirt to cut the entire plant when mowing it for hay and cutting it this short does hurt it in the long run. You can still make it work as a hay crop though by re-seeding about 1/4 or 1/3 of the new-stand seeds/acre rate every year to replace what you kill by mowing. I usually add in more Imperial clover to the mix each year too. I planted this field Spring 2010 and have seen the clover content gradually increase.
Obviously a pure clover stand would be fine hay as far as food value but the short soft structure of the plant itself would tend to make soft bales. At least if you are talking about square bales, which is what I deal with. They wouldn't stack as well as harder bales but as I said, for food value, they would be hard to beat!