I still love 3dm2k1se for system stability testing and to compare me system pre-upgrade to post-upgrade, it's about the best all-around system tester I know for D3D.
I don't like 3dm2k3 so much since it is just so graphic card intensive that it pretty much ignores the rest of the system, I wish it would be just a bit more holistic in it's system measurements.
3dm2k is still the nut-buster for me to see if an OC is good, if it can make it thru Helicopter high-detail it can make it thru just about anything....it's also great for testing older systems out with. (I build a lot of cheap web-cruisers/kid gamer systems for families that don't have PCs, my way of giving back I guess and keeping too many old parts from clogging up my basement/garage...plus it might be a cheap old PC put together from spare bits but to a 3-5 year old it is a top-o-the-line wonderbox!
So I guess I like 'em, but not 3dm2k3 so much 'cept for the fact that it's brought the whole "optimization" issue to light....I owe it a nod for that if nothing else.