For my half of the first SS we only had like 2 problems and one of them was a mix-up and not anything deliberate.
That being said, I don't know how many did the July one but I had 50 within like 5 days last year for the first SS. The pairing thing was just a simple way to keep it sane. Randomizing IMO will just end up with more admin errors which result in people not getting something.
Also, I agree with the not knowing factor. Normal gift giving is just that...you buy something for somebody and they get it and hopefully like it. Something unknown is cool because you have to think "is this a pretty universal thing?" or "man, I hope he likes this".
We honestly used very little SS stuff for ourselves, most of it ended up in my tourney prize box...which is just as good or better because I have what I use in abundance and this means the gift gave twice...first we got the excitement and joy of opening a completely random, unknown gift (not a Bill likes gazelles, lets get 10) AND we got to pass the awesome down to others who would actually use them.
Also there are always D-bags...someone will find a way to deadbeat their way out of it no matter how many regulations you create.
Keep it Christmas and less 7-day cool off for a handgun.