I've been through most of the Celestion line, and also have Scumback M75 (greenback clone) and H75 (G12H30 clone) speakers. IMO, they are special. In particular the H75, which is my personal favourite. The Scumbacks have that magic quality of being able to produce just the right amount of treble and cut, but with absolutely no harshness at all. The mids in the H75 are also very sweet (very noticeably more mids than Celstion's current G12H-30's, which are really quite a mid-scooped speaker).
I still like Celestion's current Greenback. Even though it is made in China - it's still a really good speaker IMO. Celestion's V30 is also another beaut of a speaker - if it fits your application of course.
For me, in the future, if I want greenback tone, I'll buy Celestion as the extra cost of the Scumbacks isn't worth it for me. If I want H30 tone, I'll definately go for Scumbacks though.
One of the other huge benefits of the Scumback line is that they do higher power ratings for these speakers (65W and 100W), which IMO sound near identical to the lower power ones.
Of course this is all hugely subjective, and over the years I have learned that an awful lot of people don't like what my idea of good tone is.