Dynamic Petroff Line

I play a very dynamic approach against the Petroff.  The main line of the Petroff is very drawish and the game is not very fun.  But this line lets White attack and have very active pieces.  What do you think of it?

That's what I play too, but I'm often tempted to play the Cochrane Gambit!

 I play this line too. So far so good! I have yet to have much trouble with it.

Svidler-Kramnik is one I remember

 http://www.chessgames.com/perl/chessgame?gid=1379710 

I never said it was better than d4.  But this gives you better winning chances and does not bore you to death.

another good move for an imbalance. Too few games to say whether it is better or not that good than the mainlines.

But since a super gm has played and won as a surprise novelty against the former world champion it gives it more credance. To tell you honestly, I can't find anything wrong with that move. 

but a

5. Nc3  d5 6. Qe2 and black loses a pawn.  5. Nc3 is fine if it matches your style and needs, can you use the open lines & tempo to gain an advantage as you minimize the damage from your compromised pawns before Black equalizes?

The 5 Nc3 Petrov is the height of fashion right now, having been trotted out in force back in 2007's world championships in Mexico City. Its four outings, however, all ended in draws. It is not new (actually, it's often called the Nimzovich Variation, though it's not his invention either), nor is it any kind of silver bullet against the Petrov (the percentage of draws is very close to 5 d4).

But what you need to understand is that, at the highest level of play, the d4 lines have seen massive theoretical research in the past several decades, and GMs are starting to look elsewhere for the advantage. You might remember the flurry of interest in the Berlin Defense to the Ruy Lopez (1 e4 e5 2 Nf3 Nc6 3 Bb5 Nf6) after Kramnik adopted it with some success during his "Braingames" title match against Kasparov in 2000. Before that, Kasparov rehabilitated the Scotch. These things go in cycles; and you can bet that, before too long, 5 Nc3 will fade and the Super GMs will go back to mining 5 d4 for new ideas (though they may stop back at 3 d4 for a while).

But to go back to the question at hand, I think 5 Nc3 is fine. White allows himself to be damaged, but the doubled pawn does not cripple a local pawn majority and may give him a little added cover in the event of 0-0-0. Very often there is the possibility of opposite-wing attacks if black castles 0-0. I think the important point to remember is that, after 5 Nc3 Nxc3 6 dxc3, the only player with any real weakness is white. Black is not going to crumble on his own.

 Here's a link to a heavily annotated game from the first round of the '07 World Championship. Anand essayed this line against noted Petrov expert Boris Gelfand.

(On another note, there has been some discussion of 3 Nc3...I invariably play 3...Bb4 and have achieved excellent results.)