Used them once ...... not again. The only trees that did well for us were a Nova Scotia crab and some kind of " hybrid pear ". The rest ......... NO.
For fruit trees, the nicest trees I've seen were from ACN - Adams County Nursery. ACN is on Penn State's list of the best nurseries in the U.S. There aren't many nurseries on that list - I think about 10 or 12. They raise all kinds of fruit trees, not just apples. The trees I got from them were not whips, but were feathered and had about 3/4" to 1" caliper. Never lost a tree. Cummins is also on the Penn State list.