I have been going through my rolling stock fitting Kadees for a while now and I have had all the problems mentioned above. I use the height gauge as well.
Because the length of the coupling hooks on tension lock couplings varies depending on which type they are, with long and heavy trains you can get derailments as only the shortest hook between two wagons with dissimilar couplings will be doing the work. So the point of attachment will be off centre to the track and the wagon will try to proceed crab-wise, looking for the first point where a flange can climb out of the 4 foot and derail. That, together with the ability to uncouple remotel and the delayed uncoupling feature, sold me on Kadees.
I tend to stock up in the States when I can, but I am not sure what Security will do next time they X ray a solenoid uncoupler kit in my hand luggage!
Because I don't marshall rakes of coaches, the Kadees are fitted at each end only on the Bachman Mk1s and I have had to cement a thin packing piece to the bottom of the buffer beams. My Ian Kirk Gresleys have all got Kadees fitted and they run far better than they used to with Tension locks.
All the passenger locos will get them eventually. Both Bachman and Hornby tenders on new build locos have NEM pockets at the right height. I can stop an express in my main up platform, uncouple the loco remotely without jiggling it about and couple up a new one without pushing back on the rake.
I do marshall the none passenger carriage stock and so they are all getting Kadees. I have managed to fit short Kadees onto the J72 which shunts the parcels dock and the carriage sidings. The 08 is also fitted.
Because I do not have a goods yard, I do not shunt wagons and so goods stock has three link couplings which look so much better. I have several match trucks so that various types of couplings can be accommodated on goods locos, the kit built ones have three link couplings of course.
The coaling stage is served by two rakes of four mineral wagons with Kadees at each end. With a Kadee fitted Jinty, I can push a rake of "fulls" up the ramp, couple onto the four "empties" on the ramp automatically, draw them all down the ramp, place the four "empties" in a siding behind the coaling stage and then push the four full wagons up the ramp and leave them there, all without having to resort to the "hand of God". Half the time I am placing empties on the stage and removing full ones full of reject (?) coal as I have not yet found a way of shovelling the coal into tubs.
In conclusion, it is not necessary to change all your couplings to Kadees to get the benefits of this superior system.
Colombo