Gameplay feedback: I'm a pretty decent player at the original games and I couldn't make it over a single obstacle, the controls seem extremely sensitive/abrupt currently.
What annoyed me about Trials is the artificial assist and magic forces that let you control bike midair and climb vertical walls - True Trials won't be like that, every force is derived from friction, spring compression, and weight transfer.
Making physics feel right is a hard part indeed! Balancing leaning stiffness/damping of every angle and rider's joint is tricky. As you mentioned that controls are sensitive, it's necessary to clear high jumps (e.g. first checkpoint in course3 currently). It's surely takes time to get used to.
I have a Discord channel where I will post updates: https://discord.gg/wtcZ5q5zHN.