I've had a problematic relationship with M magnet speakers for some reason, the ones I tried were either insanely harsh or insanely fizzy... Along came the Mojotone BV-25M which was neither, and it was a good sounding speaker but a bit too rounded and almost sounded like the cone wasn't moving as much as it should.
Anyway, the EVH is everything I want in a G12M speaker. It's clear, smooth and warm without being too polite or rounded. Even though Celestion have confirmed it is in fact rated for 25 watts and not 20w I would recommend not feeding much more than 12.5w to each speaker, unless you like speaker breakup of course. Running two or four of these in a 4x12 with a ≤50w amp is ideal, but I would be very careful with 100w amps (non-master volume especially). The low end can fart out if you send it too much power, but otherwise it's going to take a lot to push it into "unsafe territory" in a 4x12".
Does it sound exactly like a Pulsonic Greenback? I haven't tried one myself so I don't know for sure, but I have some experience with vintage Blackbacks and I prefer the EVH because it's smoother and more "pleasant". If you prefer rawer and more untamed tones you might disagree, but the EVH sounds more "like a record" IMHO. I think this speaker can work for almost every genre, sound and amp honestly, just depends on if you dig it or not. Excellent choice if you're a G12M Greenback guy, or just want to get off the beaten path of Vintage 30s.
