I have a v8 license and payed the full $40 price for v10 and was happy to do so. A couple days later JRiver offers a discounted v10 upgrade for v8 license holders, but I didn't worry about or mind paying the full price. Now I have gotten an e-mail saying that I have been refunded $27 to match the price difference in the upgrade and the full price. JRiver is easily the mostest awesomest company in the world.
Just to reiterate, I don't mind paying the $40 price for v10 if you want the $27 back. When I bought a copy of v8 I was told that the license included the very next version when it was released, but not any subsequent versions. I personally think that anyone complaining about not having a discounted price for upgrading from version 8 should just chill.