As to the IQP, the jury is still out on whether it can be fairly called a "structural weakness." Certainly it isn't optimal in the ending, but do its advantages in the middlegame compensate?
In any event, if you think of the IQP as a weakness to be defended, you should not be playing the Tarrasch or other lines which lead so quickly to it. You will get crushed with a stunning regularity.
Play IQP only if you are looking for opportunities to attack, to use the support points, and to advance it, even as a sacrifice, to open lines and force play. It's a position which an aggressive player can turn to advantage, passivists and bean-counters perish.
I'm interested in this position - does black have any advantage, or are pieces necesarry to take advantage of the isolated pawn.
It is not true
What's not true?
And estragon, I don't think of the IQP as a weakness, but in the tarrasch where white already has a development lead (with the first move) and gets the ideal setup to play against the isolated pawn white should definately have an advantage.
Yes, Black has the advantage without pieces, the IQP is only strong with pieces around and behind it. White will have to defend it with the King, while Black's King has more flexibility, he can go to either side without fear of not getting back in time.
But even here it isn't necessarily a winning advantage. Black will need some other target to threaten, else passive defense may well hold. So while it is fair to say the IQP is "an endgame weakness," it is not such a weakness as to mean certain loss.
Oh, yes, you are correct that the current state of theory holds White should be somewhat better. I was referring to the general case about the IQP, not any specific variation.
You are right to clarify that, thanks.
Back to the original diagrams : there are a few factors that make the Tarrasch position better than the Nimzo for White :
1- the g2 bishop pressure the d5 isolani
2-the Bc1 is free to move along the c1-h6 diagonal, particularly to g5 where it attacks a defender of d5.
3- the Nf3 can not be pinned by ...Bg4
Just to clarrify what I was saying: The IQP is certainly a "structural weakness" meaning that it is a weakness in the pawn structure. But as you have quite correctly said, playing with an IQP can be good - and ones position can still be better even with an IQP. However in that case it isnt the IQP which is giving your position the strength - it is the open lines, the control of the square in front of the pawn, the possibility of pushing the pawn, the active pieces, the outpost squares supported by the IQP and the space advantage that give the position strength - not the actual IQP itself. The pawn itself is still a structural weakness - but chess is not all about pawn structure - there are many other factors and of course (as you said) the presence of an isolated pawn certainly doesnt make a position bad - one can have a very very good position with an IQP.
Personally I love playing with an IQP - and I also love playing against one. You also sound like you know how to play IQP positions well.
Just a general note here: If you play well against an IQP, its quite easy to learn how to play well with one. And by learning how to play well with one, you will find that you get even better at playing well against one too. Its a case of looking at the position from the other side of the fence. Set up a common IQP position 10 moves in from a Nimzo/Panov Caro Kann/c3 Sicilian/QGA etc etc etc and play a 20 game blitz session against a friend of about your own strength alternating between black and white. You will be amazed how much better you get at playing one side if you train for both sides of it.