If the SR-207 is anything like the SR-407 (or god forbid the higher end models) then I totally understand and I agree with you. The SR-407 I demo'ed had a smoothness and effortless accuracy that I've never heard in any dynamic headphone. Both my HD600s and DT880s sounded congested and grainy by comparison as did all of my headphones. Electrostats are truly a different experience. To me, relatively, dynamics sound strained, as if you can hear the cone driver straining to reproduce the sounds, whereas with electrostats the sound is just there, magically existing effortlessly, as if a miniature version of the band was sitting there playing the instruments for you. Ultimately you get a smoothness and accuracy that probably not even the best dynamics in the world can compete with. I agree with you, they really aren't prohibitively expensive. I'm planning on eventually getting the SR-407 / SRM-252S setup. Having demo'ed them I know they would be worth the $1100 they cost, at least to me. Its pricey but not too pricey for what you get IMO. Were the special electrostat amp not required, which is half the cost, they would be an absolute no-brainer and an even better value than the venerable DT880 and HD600.
I've never tried this myself, but one guy I trust suggested that if I wanted to get into Stax, to get an SRS-2170 system and if I like what I hear and want an upgrade, he suggested that I upgrade the amp first.
Best sound I've ever heard out of a pair of DT880 was from the headphone jack in the Audiolab M-DAC.
At a meet a few months ago a guy showed up with a pair of balanced HD600s and about $4,000 worth of DAC and balanced amp.......crazy, but it sounded amazing!