@Marchi I have only been riding a trike since August 2018 so I still have my "L" learner sticker, about 3000 km and >900 with pedelec support:
- I ride mostly on the open road so flatter seat means faster, I would guess about 3-5 km/h faster on the plain and much faster downhill
- my pedelec motor is set to 25 km/h and necessary for the >9% gradients all around me, I have a slower average speed on the plain since I installed the motor because of the extra weight
- I learnt (quickly) that the seat as far forward and as close to the front wheels as possible means greater cornering stability
- when I ride in town I stick to the bike paths where possible which means I have had more near accidents with bicycles than with cars
- the most dangerous people are pedestrians on their telephone...
- the dangerous drivers are the ones that are dangerous for all bicycles and pedestrians, most drivers respect the trike much more than they respect my upright pedelec, there is the notion that a trike rider must be handicapped already...
I am at the stage where most tight corners and roundabouts are now taken with the inside wheel almost or 1 cm off the ground, no high speed tip-overs yet... About half my body is out of the trike when cornering at speed, that helps keep the trike flat and following cars at a respectful distance
There is a 2.4 km descent on one of my usual routes which I now drive without touching the brakes unless there is slower traffic in front of me, all corners have correct camber but when the seat was more vertical I had to use the brakes to feel safe.
Basically I am a silly old fool on a pedal powered go-kart, a speed junkie but one without a death wish.