Okay, so I recently completed my Giottos collection (lol) by adding a carbon fiber tripod (the MT 8170) as I'm looking to get into some macro... The boom is absolutely a boon. 
What do most people use for a head? This tripod doesn't necessarly need one, but for starters I like QRs. The boom vs. standard tripod is a bit of a different school of thought and they behave differently.
The thing that makes the most sense is a ballhead. You can position the tripod any which way and have the ballhead act like a gimble and keep the camera horizontal and level (or portrait, obviously). This is how I use it for the most part.
I have the MH 1001-652 medium ballhead with QR. I also shoot with a 1D2N and any one of the lenses in my sig. I find that even with the 24-70mm, the ballhead has one helluva time trying to hold the load "sideways."
I imagine a larger ballhead would be one way to solve the problem. The one I have is rated above the weight I'm using, but there's a difference between supporting the weight normally and another thing out to the side, where leverage increases the effective weight.
Another solution is to not use a ballhead, but then positioning the camera becomes a little whack (if not impossible) and is stuck to the 'pod.


