Mine is standard but has the beginings of DMF problem.Obviously not a suitable set up for my line of work.

I would definately say that yours is a DMF prob also as your symptons are almost exact to mine but i have 18 months of warranty left.

TC should only kick in when one of the front wheel starts to spin, and even then it shouldn't judder. On the Astra (which seems very similar to the 2.0TDi Octys at work), it'll allow some spin before kicking in. I can get a nice understeer drift with the ESP/TC working.

The work Octys (which I believe at 170PS going by how well they go) it'll easily overpower the grip available on the factory fit Dunlops, and will slip enough to do the roundabout drifting I mentioned above.

So, no I can't imagine it's the TC doing it, though it's hard to tell. I'd be very very surprised if Dave's diagnosis is wrong, he's been tuning VAG engines for years upon years so he knows his stuff.