I ordered two benchgrafts from them this spring. I was happy with the ordering process and the plants arrived well packaged. However one of the rootstocks was quite inferior, it had only one small root on it. I have done benchgrafts for myself, and when I run across an interior rootstock like this I set it aside as a "backup". Unfortunately the plant died not too long after planting it. I wrote them a letter and got a polite reply about how I probably watered it too much etc (I didn't water it much at all) but they did refund the cost minus shipping. The second apple benchgraft has recently died as well. This one I would call a bit my fault because it has been very dry and I probably should have watered it a bit more. But I have grown out many of my own benchgrafts (literally hundreds) and had much better odds.
So overall I think these people are trying to run a decent business but they need to produce higher quality benchgrafts if they want to take the risk of selling trees in that form. I also wish they would sell scionwood instead, for people like me that know how to graft that is a much more reliable method.
I haven't ordered from this company, though I intend to in the future. They are very knowledgable and generous with advice. They charge a few bucks for their catalog, and don't have a website, so they aren't as easy to get to as some. But they did send my catalog on the honor system, so I could get it promptly. Furthermore, they will custom graft a tree to the variety and rootstock specified. Good selection.
Greenmantle Nursery has been inadvertently slighted by the Seed Savers Fruit and Nut Inventory book. If you look through, you're likely to find varieties you're interested in with Gr4 listed as the source. But then, in the part where the information on the companies is compiled, there is no listing for Gr4. Now you know!