Personally, I think the versatility of a clip release lanyard wins hands down in daily working situations. Why? Because like you say Nick, the versatility.
Many times there are situations where the lanyard is a little high and unsuitable for side Ds, a temporary sitting position is required.
Other times, particulary side pruning conifers, the lanyeard can be choked and clipped single leg to the front D. This has the advantages of preventing the lanyard slipping down onto the saw, and a better position to fall into if you cut the lifeline. Choking on the bough you are cutting is better if that bough should split!
Just some thoughts to consider : )