In reply to UKC Articles: Oh heck here we go again...
Rethreaded Fig. 8 without a stopper knot- correctly tied and well dressed with a reasonable tail is fine to climb on and some people feel its easier for the climber and there partner to see at a glance if the rethreaded fig. 8 is correctly tied. Its also less bulky.
Rethreaded Fig. 8 with a stopper knot- a belt and braces approach with the stopper knot increasing safety if the main knot is mistied and the stopper shows that a sufficient length of tail has been left and serves to tidy the tail away.
Pros and cons add your own then take your pick.
Threading bottom up. In my experience this seems to be the 'natural' way for many to tie in. When you look down its often easier to see the bottom/leg loops and that is what many people automatically reach for.
Threading top down. IF you forget to thread both bits of the harness then arguably its better to have the belt as the only bit threaded as its higher up relative to most people's centre of gravity so if they fall on steep ground there is less chance of them inverting. Many CWAs/SPAs are introduced to this argument and teach top down threading because of it and word has spread.
However anecdotally (and from few non scientific tests I've done) if you forget to rethread your knot beyond the first pass then if you have threaded bottom up there seems to be more friction and even an untied knot may hold a fall. (Have a play with that one at the wall and scare the floorwalkers
.
Again add further pros and cons and take your pick.