Looking at this forum I just noticed this thread and would like to contribute, as I play with GD612 for the last 6 months. I just copy most of the reflections I published some time ago on TableTennisTalk:
I play both sides attack, mixed with blocking and from time to time with defense, inverttedf on FH and LPs on BH. I've been looking for some 2 years for a a good LP suitable for attacking, I finally ended up with a Guillotine S (excellent rubber, by the way). I bought the GD 612 in December 2011 but it took me more than a month to put the rubber on, as I didn't want to spoil my game during the league matches. But when I finally decided, I'm really happy with it. I can play rallies almost like with the inverted. The block is much more sure than with LPs - and it can be any type of block, though I usually use a flat or punch block, all of them are dead or have some backspin. Banana flip is excellent - if flat it comes like it had some backspin, if looped, it has also a side kick, and as it's slower than after being hit by an inverted, it abruptly changes pace and as a result the opponent often misses the ball at all ! What is astonishing with this rubber, I can chop away from the table with more control than with the LPs (I've been recently watching and imitating Hou Yingchao and trying to develop a similar control of the ball with BH, he uses Spectol for chopping). I'm not relying on deception, but it's a nice bonus, and players who are accustomed to LPs are usually surprised by the aggressive style allowed by this rubber.
A difference from LPs, after all 612 is an SP, or more probably a MP - chopping against a loop doesn't give a high amount of backspin, but control well compensates this, and as I said - for me this type of defense is ususally the last resort. Of course I'm talking about a rubber with 1.5mm sponge, probably it will be better for choppers with an OX, but with my style I would be unable to use it.
To finalise - if you look for a more aggressive rubber allowing you not only to block but also to flip and punch - it's the one. If you play more defense, heavilly chopping, better choose some LP.
Next week I will finally get hold of the turbo version and be able to see whether it's as promising as the regular version.
How well does it flick (pick hit) or smash?