Deluxe and the System Spigot smokes about the same. But internally, they are slightly different. System Spigot doesn't have "condenser" bit at the end of the tenon. But honestly, I don't notice any difference while smoking.
You are in UK. Of course, they won't sell you a knife set. They are designated as deadly weapon in UK. I hope they will let you keep your butter knives :) With NHS, British teeth don't look like much of a cutting tool. J/K!!!
It all depends on the pipe and the person smoking it. I always clean as soon as I'm done smoking. And I do take my pipes apart middle of smoking also. Some times, the tenon will get stuck. I think that's fashionable like JRRT.