For anything above 12#, I use a Rapala digital fish scale, goes up to 50#, also very repeatable. Good for weighing guns, and I also use it for determining weights of all those "extra" 1911 recoils springs lying around..............
The reference in Kuhnhausen is volume 2, page 171, note 5, "Trigger pull checking note:"
"Pulls of 5 lbs. and higher can be optionally checked using a Brownell's recording trigger pull gauge or a std. ordnance/NRA weight type measuring system. Pulls of 4-1/2 lbs. or less should be checked with an ordnance or NRA type trigger pull weight system, only."
For a thirty cent increase, I'll go with Kuhnhausen.
I really prefer the NRA dead weights. I find them to be the most consistent and there really isn't a whole lot that can go wrong with them. I don't think they're the cheapest option, just the best IMHO.