listen back to alot of the mille plateaux stuff and it's lost it, the force trax stuff as well
i would say
some of the MP stuff lost it. some of it is still relevent I think - the tribute to Gautarri still stands tall, all the clicks n cuts I still enjoy from time to time, Frank Bretschneider albums still sound very good, and I will always have a soft spot for all that "electric ladyland" industrial hiphop. and of course, all but 1 or 2 of the Ritonell releases I consider timeless.
mouse on mars still sound OK for the most part.
sahko is not IDM but I love so much on that label
and to give back some props to Warp, I accidentally heard the first A.I. comp the other day, which is where all this started I guess, and it still sounds good!
as does Skam's 1491 or whatever it was called. solid.
but the likes of Plaid are pretty much worthless (save that track they did with bjork)