Thanks for posting your opinion!
First, and i know this is purely subjective, but i find the asking price too high for what's involved. We don't really know what's involved, and that' is the part that bugs the people: what exactly are we buying? And you're absolutely right in that it's far from cheap!
Second, i bought my HP1000s because i like the way they sound stock, not beeing able to compare a moded pair to my stock one (if you want we can arrange something, I live not too far away from you ;), makes it a risky proposition, because what Joe percieves as an improvement, might not be one for me, after all, some peoples prefer the sound of older RS1s to that of the ''i'' or improved models, of course, this goes for all ''i'' models. I agree; for me it is not that clear if it's really an improvement, though I would like to just "believe it", I'm staying critical.
Third, i have read that for some Joe took around three months to complete the modifications, and altough i hope he stays with us for many more years, i can't help but think what if something happens while he's working on my HP2s. Joe will probably stop offering and making upgrades before "something happens", so you would get refunded and your headphones sent back to you if he decides to stop it or "runs out of parts". No biggie ;)
Fourth, altough unlikely, for some reason, i'd be affraid they would get lost in the mail. Yeah.. that's a risk involved with most discontinued and rare headphones you buy remotely on the internet, and a stressful experience.