I first used these couplers WAAAAY back when they were first introduced and known in those days as the 'Billingborough' coupling (after the village in Lincolnshire where the original inventor lived).
For those not in the know or who may only have heard of the Lincs. Auto Coupler via this discussion, may I offer the following based upon my own experience with them:
1) Assembly is very quick and easy, provided you have the 'jig' (which really is essential).
2) They are so simple that not only is it brilliant, but they are also virtually fool proof.
3) They proved (for me) to be totally reliable in operation.
4) They are mounting-tolerant, both in terms of positioning along the buffer beam and (within reason) in terms of height.
5) You can indeed have a fixed hook on locomotives and operation is unaffected. You could also in theory have a fixed hook on one end of a wagon and a full coupler on the other (but the wagons would then all have to run the same way round every time - i.e. you cannot have two fixed hooks coming together).
One time I took even this further by having a fixed hook protruding from under a siding's buffer stop which was situated at the uphill end of a slight gradient (not particularly prototypical but I wanted to provide a talking-point). This affectively held a string of wagons shunted uphill to the buffers. To disconnect and drive away all you had to do was back the wagons up slightly to the buffer stop, which created slack, thus allowing the wagon coupler to be depressed by the magnet in the track directly below - and off goes the train. The principle here is that the couplers will not depress whilst under tension. It was a deliberate gimmick - but it worked and as I say, was a talking point at shows.