From a novice perspective, and I am definitely a novice on the lap steel, these strings sound just great to me. They have a nice resonance and the slide moves around on them with ease. The tone is deep and quite earthy, not particularly "bright" (although they are not lacking in treble they don't sound overly trebly as some new strings can, which I don't really like)
Bought these for my Harley Benton lap steel and they suit it perfectly well and were easy to fit. I'm not experienced with more expensive strings but from a sonic point of view and with knowing how a lap steel "should" sound (as opposed to how it sounds when I attempt to play it) I would say these strings are a very worthwhile investment.
I'm not sure on the longevity of the strings as yet but I'd imagine as with most lap steel strings that they'll last a substantial time compared to my guitar strings as the playing style for lap steel is very different and less aggressive/wearing on the strings (I play mostly death metal/grindcore stuff on guitar and more country stuff on slide).
Simple, cheap and effective - why pay more ?