Sounds like you're doing my thing: making sure that you have absolutely EVERYTHING because you know that the people that you're with (in my case my family) are going to be carrying the bare minimum or less. I'm the walking drug/grocery/camping supply store...who's the only one who remembered to bring moleskin even though he never seems to need it himself? Who has several spare lantern mantels in his bag? I'd like to think that my group thinks of me as resourceful but it's more like paranoid and obsessive.

But, sorry, I guess that I misunderstood the point of your query. I wouldn't think that the buckle on a regular pack waist strap would be uncomfortable but I would be concerned about the wear and tear on the kilt material...I've had camera bags that have been made of the rougher waterproof nylon that have rubbed holes in the clothing that they've been in contact with...those straps seem to usually be made of the smoother stuff, though.

Best

AA