When I first switched from the old XT brakes to the current Shimano XT brakes the new ones felt a little lacking in feel. I found the initial bite was much more powerful than the old one and was hard for me to modulate the brake.
I soon recalibrated and now have plently of feel from the brakes. I can easily modulate them from a fine feathering to a full hard stop no problem. Give it a few weeks and you’ll get used to them.
You can play around with the free stroke adjuster but I find this mostly does nothing so make some large adjustments to the screw and even then it’ll probably feel the same.
Regarding the juddering, make sure everything on the back end is tight, including rear axle, any cup and cone bearings are done up tight etc. Also could be the rotor, some rotor shapes can cause juddering.