Well, I can speak of the Blaze Custom. I've got a '91 UV7BK and, a few months ago, an RG7-620-GN; just before getting the RG7, I put a Blaze Custom into the UV, and was astounded by the effect. Enough so that it was the first thing that I did to the RG7, within days of purchasing it - I ordered the replacement pickup as I picked up the guitar itself, in fact.
Compared to the UV's Blaze in the bridge, the Custom has VERY much the same tone, but it's got a much hotter spike in the midrange, the net result being that it sounds much tighter, and to me (and my 'test ear' friends and such) holds together on the low end in a much nicer, smoother way. *It's a big, wide sound that works very well for my purposes, especially since it has quite a bit more output than the stock Blaze - BUT, retains a good deal of its timbre, which is so appropriate to the 7-String.
It also cleans up very nicely with a slight roll-off of the volume, and in split-
coil mode (with the Blaze single, and in the combined RG-wiring scheme) works extremely well. It replaces a Blaze very nicely.
I get the impression that the Evo-7's emphasis is largely in the upper end, so if that's what you're after, that might be where you want to go. For me, the drive and the meat and the natural compression are all at the mid-to-upper-mid range, and that's the Blaze Custom's forté.
Hope this sheds some light.
=]
