Are KT-88 a good substitute for 6550c?

I have a VTL stereo 150 amp that uses 8 6550c tubes. I usually replace them with the Selvtlana 6550c. I was told that the Electro Harmonix KT 88 was a better sounding tube, more romantic less punchier than the 6550's. I would like to try them but don't know if this is a good idea changing tubes.
Does anyone have any expierence with this.
You might take a look at and the tubes forum. A search on 6550C or KT88 will turn up a great number of opinions on just that comparison. I found over 200 hits on just a quick search.
I've compared Svetlana KT88's and Svetlana 6550c's in my Rogue M120 Magnum amps and preferred the Kt88's easily. My experience between the two types was excactly as Rcprince described above. The Kt88's richer and more analogue sounding, the 6550's brighter and less refined.

I have my shares on KT-88s and 6550s on my SF Power 2 and my previous ARCVT100.
From my experimentation and my music taste, I liked Svetlana KT88s and JJ Tesla KT88s the best(out of current production tubes).

Svetlana gives little warmer and weighted presentation of the music where as JJ Tesla is more detailed.

According to the "tube Substitution Guidebook" by HA Middleton, 6550 is an excellent sub for a KT-88. If you are worried about any harm/damage, don't worry. Switching these will only change the sound, not the electronics.