i'm very lucky and pleased, that I'm about to get a pair of black dsp7000's soon. (from an Austrian Meridian dealer)
With special thanks to another Hitchicker here..

I can't wait to get my M60's upgraded, I think also the 7000's match much beter with the 5500HC.

I have never heard the 5500's/6000's in my life, but since the electronics might be almost the same.
I still think the cabinet is newer/beter of the 7000's, and perhaps also the firmware is better.. ?

I have heard the 7000's once in my life, and they sounded incredible, very dynamic and clear and natural to me.

#1 568.2mm, HD621, G91DH, 513, 511, DSP3100 , DSP33C , DSP33, 2x MJ Pro 50 MKI, M1500
#2 G68J, HD621, DSP3100, DSP5200HC, DSP33, 3x MJ Pro 50 MKII, MS200, SB Touch, Vertex 2
#3 G61rsl, HD621, 596P, DSP7000, DSP5500HC, DSP33, 2x MJ Pro 50 MKII, M1500

Applied mods: NOS-SRx Filter by Mr. Apodizer
Mr. Apodizer Digi box