For the last several months, I have been working in a full body safety harness and safety lines. It has been extremely convient to use the Camelbak sip bottle. I can easily with one gloved hand, via a small carabiner, snap the Camelbak on and off my harness whenever I need a drink. With the Camelbak's hard loop top, I can also place the bottle on fairly steep roofs and be assured it will not roll off when I must cram myself into tight quarters to work.
The down side is you must pay attention when cleaning the bite valve and straw. You don't just place it into the dishwasher. The Camelbak does not hold as much liquid as the Nalgene bottle, 750 ml verses 1000 ml. Also, I don't think that the Camelbak will survive a thirty foot fall on to concrete as well as the Nalgene bottle. I don't know for sure since I have not dropped a bottle yet, only hammers and chisels. Ah, the joys of tuckpointing.
For one handed use, I highly recommend the Camelbak bottle.