...Actually, combined with a harness tether I suppose it could work out OK...
unnecessary 'complexity'. KISS
Like I mentioned, clipping the halyard on was not an idea that I thought up in my na´vetÚ. It was suggested by a couple authors of popular cruising books, and has apparently been proven to be effective for small boats where the narrow foredeck makes it difficult to size a harness with enough room to work without being long enough to be dragged in the water.
This evening I switched out the snap shackle on my spare halyard with a quick release shackle like the one on my tether, and adjusted its length to allow me to go to the furler drum if needed, so it's ready to go. I'll see how complex it is and either use it or abandon it (or hopefully won't have to go to the foredeck at all while underway). But meanwhile, it's attached to a stanchion available as needed, just like it has been for the last 3 years.
...if you use only a 'climbers' harness, if you go overboard and get dragged along youll be dragged mostly 'foot first' or 'jackknifed'..
I never suggested a climbers harness. That must have been someone else. The harness I bought has the rings and horizontal chest strap level with the base of my armpits, which is a very comfortable location for me.
...After a fair bit of experimentation with an assortment of solutions, I've arrived at the conclusion that fixed tethers at the base of the mast, and another in the cockpit, are the way to go on boats under 30 feet or so...
I'll be singlehanding for the first time this weekend, so that's why I'm using harness/tether for the first time. I'm taking a "kitchen sink" approach with more ways to attach than I will probably use. But I'll see what works best and what's more trouble than it's worth, and then strip out the ones I don't need. I've rigged clipping points at my steering wheel, traveler, and mast and will add a couple fixed tethers too. At present I still need a jackline to get from traveler to mast and mast to foredeck.