[projectRDM]

A one piece shaft does not hang down any lower than a two piece, in fact without a carrier bearing there's more ground clearance. A properly balanced shaft, IE one you take somewhere to balance to your car, will give no resonance or noise. It's lighter, can turn quicker, and has no free play or slop off load or on. The U joints are rebuildable and servicable, and the yokes are easily replaced.

There is nothing to justify not using one, period. Everything about it is a plus.