oh ya, stoking the fire .... making it personal there huh.
ya, advertising is what it is, and a good record is as well
upwind and in front until you're confident the person you are responsible for can comfortably handle a kite. downwind side still better than behind, but not until your person has everything under control.
from in front the client can see you, therefore you can positively influence their mental state, keeping them relaxed and happy, not stressed. you are also in the right position to hold the sheeting line at or just above the harness loop, putting your body weight directly on the kite and not on the rider, you can also block the client with your shoulder to give them support if they are moving / falling forward, you can also access the control bar and the flying lines to manipulate the kite, and you can access the primary release. doing it this way you and you're client wont go for unwanted rides, and your kites wont get slammed (as much).
I don't use trainers in our school because we don't need to, we take pride in teaching our clients to fly 4 line kiteboarding kites, and accomplish not only riding but good kite handling and decision making, and doing it with less overall time invested, energy expended, suffering, and cost for the clients.
I don't hate trainers, and any kite flying experience is somewhat valuable, but 2 line stunt kites on a bar have very few similarities to 4 line LEIs. the possible bad habits / expectations mostly revolve around holding on tight, constantly holding on, always holding on with 2 hands etc. seen plenty of people go for hard runs and faceplants thanks to trainers, while watching many clients successfully learn and become kiteboarders without every crashing themselves hard on the ground.
use em if you need to, we don't.
and we got tons of gear, including kickass waverunners radio helmets vests, everything. it is used when its necessary. there is always something downwind somewhere, the question is how far and how windy is it. (and these days: is that even an actual picture?)