I'm hearing you Harley . I'll likely sell the SRH1840 when I get the HD800 (might be another year away). Eventually I seem myself rebuying the HD600 - but not until I have the HD800. I see no real point in having both the SRH1840 and HD600 at the same time.
I think my stopping point will be:
HD800, HD600 and Alpha Dog.
But I think if I had to stay with what I have right now - I'd still be perfectly happy.
SRH 1840 reminds me of a cross between the HD600 and DT880 - but more refined than both.