For the average bloke who does average shooting I call out right bullshit on the double being faster with 4 shots. Yes I have seen the Videos but these are not average blokes who does an average amount of shooting.
Now when you talk about blokes who practice and practice then clearly the double is faster with high energy recoil calibres. However if the bloke with the double fumbles at all the bolt gun wins. The double will have the advantage in getting back on target as you just deal with recoil and not working the action as well. For reliability, that, on the surface will go to the bolt gun. Yes. The double only needs a very small amount of grit in it and it won't close. Not from my experience but from a long time African hand who trusted a bolt over a double for that very reason. Had a couple of bad experiences with the double.