Robert, very solid advice indeed. I own probably 10 or so utility knives in several brands and shapes. Being a "knife nut" it is more of an experiment in my stubbornness to find a knife capable of this then to just fall back on the old reliable utility blade.
I remodel bathrooms right now, I do not hang sheet rock for a living. I usually have to take a sheet or two and make a few panels or filler pieces. Four sheets is the most I have used in one day and I guess im looking for a traditional that can handle that one task of my day. I have no other hangups and my pocket knives handle every other aspect of my day and do cut the sheetrock now, just not efficiently or cleanly.
I understand that the idea of being stubborn and wanting to use your favorite knife for everything. But, like saws or chisels, some tools are just better suited to a task than others. For a piece or two, I used to use my CASE stockman or large copperlock with a pen blade. I found that I ground off the sheepsfoot too much with just a few cuts and liked the spey better as it sliced into the paper. Ditto the pen on my copperhead.
If I had to carry one, I would stick with the large stockman pattern. For your work (and mine!) you can cut a few pieces of rock with the spey (the curved edge not only lasts longer, but cuts better as well), cut a lot if batt insulation with the sheepsfoot and use the large clip for just about everything else. I did that for years with a large stockman and never felt under gunned, but I got tired of tearing up my knives, too. Also, a couple of my old CASE knives lost that pretty mahogany bone they used for a while when I had to clean off tar and butyl caulk with naptha or charcoal lighter fluid. The tar and adhesives melted into the the scales and them a color of dark brown that just wasn't pretty.
I keep two different models of utility blade knives in my truck. One with a thin flat blade for sheetrock,etc., and the other with a "hook" type blade for vapor barrier, felt paper, shingles, SBS, etc.
My traditional patterns aren't really hard work knives anymore for a lot of reasons, but I will do anything needed with a $7 Stanley retractable knife, and it has a special place in my nail bags or back pocket when I do the work that screams for it.
Robert