With a 72x36 Maple butcher block top from Amazon - http://www.amazon.com/Relius-Solutions-Butcher-Block-Maple/d...
The top easily weighs 200 pounds, and that's not including the 2 Thunderbolt displays that sit on my desk.
It's been a great platform. At my standing height of 45", it needs to be up against the wall or it would likely vibrate a bit. As it stands, it's great.
The pushbutton memory allows for fast adjustment between sitting and standing. I probably transition a couple of times a day. If I'm going to be on the phone a while, I might sit if I'm not pacing.
Even if you simply used it as a regular desk, one of the things that have become most apparent to me is the difference tenths of an inch make in getting your workspace dialed in. Maybe you're wearing different shoes - or no shoes - you can dial in your desk appropriately.