Have I?
I just ordered an RS-1 tonight, without ever touching them.
I've heard: Senn HD600, HD580, HD590, Grado SR-60 and SR-80. From what I've read here and elsewhere, most of what people have to say about these phones match what I've heard. Although, I haven't heard any of these phones (save the SR-60) through a headphone amp.
Sans amp, I preferred the sound out of the Grados, so I just made sure I ordered the RS-1 from a site with a 30 day return guarantee, thanks to joelongwood's direction.
For those of us with limited time (me) or resources, "buying blind" may be the most convenient way to check out new phones, as long as you set aside a few minutes here & there to do a little research first.
Would I?
Depending on how my RS-1 experience goes, I may invest in a matching RA-1 amp next year, also blindly. If that goes well, I may also (blindly, most likely) order a Senn HD650 and give those a try through the RA-1. And if _that_ goes well, I may get another headphone amp that matches well with the HD650, although that will require much more research on my part. While I preferred the Grado sound over the Senns, I may appreciate the different sound of an HD650 through a matching amp.
Ahh geez. I just mapped out my financial woes for next year.