The only mention of it (grafting) I found I also posted here--this website but not this particular section of these forums.
It was promptly deleted by moderator--indicating the url I posted was illegal, in- appropriate, etc., etc. Also said I was politically motivated in so posting it.
I did also post it at my own site somewhere.
I haven't seen any info on using Hops as rootstock.
Grafting to rootstock is commonly used on citrus trees, but hops are so hardy on there own, grow true to the species of rhizome planted and AFAIK don't have any compatible species to graft with. The grafts would have to be made directly to the rhizome in order to last more than one season. Otherwise you would have to graft onto new bines each season.
If anyone has tried this it would be interesting to see the results.
It depends on what you are looking for. I know a lot of commercial watermelons are grown from grafted transplants where the desired fruit type has roots that are very susceptible to disease so they graft that on to a variety with a more resistant root system. Tomatoes have been grafted to jimson weed (related genus - and hallucinogenic) with bad results. Apparently if you graft high enough on the jimson weed stem so it has leaves on it, the nasty suff will show up in the fruit. No leaves - no nasty stuff.
I actually do research on grafted apple trees and here the rootstock can have a great affect on the scion. It probably isn't worth it, but if you had a great variety that didn't grow well, you might be able graft the shoots onto the shoots of a more vigourous rootstock. Or if you had a variety that was prone to diseases, you might be able to graft it onto a more resistant variety. This last one is a large focus of what I do in apples - at the molecular level.