I have used them, but my cider's are all still in the secondaries. The "tasting" leftovers from racking proved to be real dry, but not puckery.
Yes, they are expensive too. I had several 5 gallon batches going, so I made the plunge and bought them. I used the Wyeast cultures, and I even pitched a second batch on the lees from an earlier batched. Both ciders were racked at the same time. Time will tell.
Primaries - all empty
Secondary - Several Hard Ciders
Bulk Aging - Brewtopia Barleywine