So in short you want a bike which (1) has better reach and fit (2) folds faster (3) folds tighter and more elegantly (4) has less stem play (5) has larger or cushier wheels which deal with cobbles better.
This bike does not exist.
You will have to give up some of these goals in order to achieve others. Here are the primary options I think you have:
- Mounting Big Apples or a similar fat tire on your Vitesse, as well as an Aber Halo stem. Satisfies #5 and maybe #1.
- Bike Friday Tikit. Satisfies #1, #2, but in standard configuration is a bit worse for #5 (about the same when using Greenspeed Scorchers).
- Bike Friday Pocket or NWT. Satisfies #1, #4, and in some cases #5. Worse #2 and #3.
- 24" folder. Satisfies #1, maybe #4, sometimes, #5. Worse #2 and #3.
- Brompton. Satisfies #3 and maybe #4, but has worse #1 and #5.
I suggest before you buy a new bike, talk to Thor about (1) adding an Aber Halo stem (2) getting cushier tires, and (3) fixing that wobble problem, which sounds like a manufacturing defect.
Barring that, if geometry is a big issue, then it's time to talk to Bike Friday. I am partial to the Tikit and have ridden it all over the Left Bank and Saint Germain (and a half year in Rome), but YMMV. Though I have the Hyperfold version, which is awesome, you should get the Model T "twiddly knob" version, as it has a bit less flexy stem. Even so stem flex may drive you nuts. Other Bike Fridays have stiffer stems and bigger wheels.
I don't know if you'll be happy with a 24" folder. You may find it so bulky that you'll wonder why you shouldn't just get a mountain bike.