Not too impressed. A bit of history, so you know what you're looking at, and who you're listening to. This is information that is often overlooked in reviews, and can account for a lot of misinterpretations. I rely on reviews heavily, and I wish more people would put background info in. I've been playing EB for about 15 years, upright for a couple. I have a Shen SB 80 setup by Upton. They sent it with a middle of the road setup, Helicore Hybrids, and their wing piezo pickup. It plays immaculately, and sounds like a new, cheap plywood bass. Not very complex. It does the trick. I've played nicer instruments. I've HEARD much nicer, but it's what I could afford and it's fine. I hate the Piezo, and always have. I've never tried another piezo on this bass. I'd like to, some day. I currently use a Krivo Mag. I played in a folk trio/alt rock singer songwriter/traditional Acadian fiddle band with it as I purchased it. The Helicores were tough on my virginal fingers so I got some Velvet Animas. Loved the tone and feel, but when I joined a rockabilly band, I needed to go mag due to feedback issues. I got the Krivo and Blast Cult Low Life steels. Loved those strings. Sounded good, nice and loose for slap. My favorite for rockabilly thus far. Only drawback is they came unwound after about 11 months of light gigging, which many say isn't bad, but I thought it was premature. So I put the Helicores back on. Decent slap tone, though high tension, my fingers are stronger now and could handle it. Only real problem was I got NO fingerboard click with the D or G strings and I didn't like that, even with the K and K piezo under the fingerboard. I started looking at superior tri cores, and other weed wackers that would work with the krivo. Superior had a long wait time and were out of materials for the D and G strings so I ordered the far cheaper Slap Happy strings, which had a decent acoustic sound based on a youtube video comparison to guts. Admitedly, acoustically they sound ok. Not a ton of volume, but my bass doesn't seem to be very loud anyway, regardless of strings. I put the piezo back on, for giggles, and the sound was ATROCIOUS. Plasticky and aweful, with tons of finger noise and just plain bad. I hate the sound of the piezo anyway, but this was even worse than with other strings. Through the mag, the tone is pretty decent, on the A string. Good woody click. D string is ok, with less click. G string is ok with almost no click. E string sounds completely dead and lifeless, weather through a pickup, or unamplified. Just totally limp. I'll be interested to hear them in the band setting, and hope they grow on me as they break in. It's been a couple of weeks though, and they've stabilized and I'm still not real happy. I've never played guts or even other weed wackers so I can't really draw any valuable comparisons there. The Blast Cults were better tonally, and more playable, but the click wasn't woody and traditional enough for me. I like the A string click of the Slap Happys but that's about all I can really say for them. I don't hate them. Not flaming them at all. Just not really impressed. I had high hopes and am a little let down. They definitely work with a mag though. I'll try to remember to update after my gig, and again if my opinion changes over time. I'd like to try the tri cores for comparison for sure.