RTD is super tight/rigid in my F87 M2, no play, I mean, not even a little, I have the V4 carbon version, drop-in style, package come in pre-assembled and DSSR pre-adjusted.
My friend went with CAE, great top of the line product, except it needs a little bit trimming.
I think CAE is more DIY, you can adjust anything according to your specific needs, shaft angle, side gears tightness. It can work on any platform/chassis.
RTD is like 50% adjustable, F87 version has adjustable length DSSR too. but I didn't bother to mess up with it. If you simply just want a plug and play style, RTD is good enough and with half of CAE cost.
Kinda suprise that PSDesign has so much free play in gear. mine is solid like rock, sometimes I wish to have a little wiggling room, save me 10% of strength swimming gears.
I have ASS from Ronald, It's really the best OEM+ shifter and customer service is platinum, quick email reply, details explaining, you will have a lot of support from him to decide which stuff you should pick to meet your needs.
But chassis mounted is just different. for those just shift like a bolt rifle and don't give a shit about NVH people. More connected I would say