I have a very different kind of suggestion on the upgrade system: The strength of an item depends on the number of usage. More you use an item, higher exp and level it is. The level and exp will be reset if you trade or sell that item. I don't think dbog can do this, but I think it may be interesting.
I'm just highlighting.
Well, if the problem is changing the difficulty of the upgrade system, make it +20 or anything. I won't support any more wipes.