Every Grado I've ever gotten rid of/auditioned I haven't missed. They've never been my cup 'o tea except maybe teh RS1. It's that flexibility from the HD 650 that makes it hard for me to imagine ever getting rid of them. I've yet to find a headphone where I can confidently say that it's a clear replacement for my HD 650. I always go back to them.
Yeah, if I make it to that Charlotte meet, I'm very curious to try out the HD800. I still need to get a dedicated DAC, too. And I really loved the SR325i's. If I try another Grado, though, it'll have to be much warmer...and just as comfy...haha.