The CCE mod only works with those tubes that have the floating grid, so only the sv83's will take advantage of it, while the other tubes you've rolled would not, and it would sound like it does now with them installed.  Since you like the SV83's anyway, I would do it to squeeze out that extra bit of performance available.  As for that extra bit of performance, the improvement is subtle, but I felt that the most striking qualities of the amp, namely imaging prowess, was slightly enhanced, expanding the back of the perceived soundstage rearward, with a slightly greater sense of space and the precise rendering of ambient cues on the recording.  I remember when I first fired up the amps after the CCE mod, it sounded like the curtain on a live performance was opened, in a seemingly large venue, as though the wall behind the speakers just fell away.  Of course I could be victim of preconceptions with my perceptions, but if you personally find no benefit, Steve will undo it and refund your money, but I don't see it happening.