They're pretty dead sounding on a split coil P-bass, but with the single coil pickup on the '51 reissue they sound really bright and thumpy with a nice growl.
I've used them on a circa 1969 fretless P-Bass, a 1979 fretless Stingray and a Kyddbass (stick upright with piezo). All I can say is that I didn't like them on any of those basses.
The Kydd came with what I assume were Chromes (that's what he lists on his website). I liked them just fine (the G was missing). They had a nice thumpy upright vibe that I didn't mind at all. A few remarks I've come across makes me concerned about their longevity. The joy of flats is that they are a long term relationship.
Since I'm on the subject of "flats" that I've hated - GHS "Brite Flats", which are a half-round. Ugh! don't bother.
I've tried LaBella Deep Talkin' Bass. I didn't love them, but I didn't hate them. They weren't for me, but I didn't think they were no good for anyone. Until this thread I didn't think anyone could love the Fender 9050's (we are talking about the same string: "9050s" Stainless steel flats, right?). This wasn't the case for the LaBellas - not for me, but they have their own funk that I can see people really loving.
Wow! I didn't think I had as much experience with flats as this thread is making me recall. The Lakland Joe Osborn's are still my favorites. Sadowsky and D'Addario Chrome (a friend suggests GHS's flats, which I've never tried either) are on my "must try" list.
Everything else is just wrong.
I kid, I kid!
But I've gone years and years with the Laklands and have felt no urge to replace them. They are the string I keep coming back to. I've never gone with the entire heavier set. The lighter set is too light on the G for me. The Hybrid set (not offered outside a special order) has been great and I have had no urge to try the heavier set.
This thread is making me realize how much I love the flats I use.
As a total derail, I liked the stainless steel lighter set of Lakland's rounds I used on my 55-01. I'm using SIT strings on it right now and I hate them less than I did when I first put them on. It always surprises me how much a standard 45-105 set of GHS Boomers feels like coming home. I haven't intentionally strung up with them in years, but every time I come across a set, I feel comfortable. It's what I started with and they still just seem right to me.
KO