I use Thomastik Jazz Swings on a number of guitars, and love them. They are stable, have a great feel and virtually immortal. How immortal? The set on my Country Gentleman are 12 years old, and still sound great. I’ve replaced the top three (plain) strings a number of times, but the bottom three sound like new. Thomastik Jazz Swings have the attack you would expect from a flatwound, but they are not at all dull sounding. Just keep them clean and they will last a long time.

I have used Pyramid Fusion Flats on a couple of guitars, and likewise, am very impressed with these, as well. Fusion Flats feel more like a round wound, but the other layer is actually a flat, pure nickel tape which slightly overlaps the preceding layer, leading to a round wound appearance, but they sound great; somewhere between flats and rounds, and the overwound outer nickel layer should equate to a very long lived string. I have these on my Warmoth Jaguar along with a Tele Thinline, and they truly sound great.

Both Thomastik and Pyramid are old school string makers, and seem to follow a more orchestral way of looking at strings. On double basses, string changes are very rare. A friendly acquaintance had a five string double bass and the low B was starting to show signs of impending demise when he replaced it. That string was 36 years old, before it became a problem. This sounds insane to most guitar players, but it goes to show that there’s a different mindset when it comes to orchestral strings, than what we are used to with guitar strings.

My advice would be to go for it. There is a big difference among flat wounds.

The artist formerly known as: Synchro

When Surf Guitar is outlawed only outlaws will play Surf Guitar.

The Ernie Ball guitar flats are pretty terrible. I recommend Thomastik flatwounds, particularly the George Benson set because of the heavier bottom.

Flatwounds have a distinctive sound and feel. I definitely prefer them for jazz guitar - think Wes Montgomery, Barney Kessel, George Benson, and so on. I tend to like them on jazz archtops, Gretsch guitars, and usually keep a Tele and a Strat set up with flatwounds.

I like both flatwounds and roundwounds for surf guitar, depending on what I'm going for. For the most part, I go for relatively heavy strings - typically a 12-52 or 13-56 type of set. But I usually cut the gauges back a bit for the middle strings - more like .022, .030, .040 instead of .024, .032, and .042 on strings 3-5 for the 12-52 set, and proportionally lighter strings 3-5 for the 13-56 set. This is to even out the tension across the strings - most guitar sets have higher tension on strings 3-5. If I want to be able to do non-wonky whole-tone bends on a Strat or Tele, I'll use a .020 or .022 plain 3rd. But more often than not, I just use the slightly lighter wound 3rd. The wounds are bendable, but sound very different than even the heaviest unwound 3rd. I don't tend to use offset Fenders much, but when I do, I almost always use flatwounds.

Flatwound strings tend to sound and feel smoother, and relative to typical nickel-plated roundwound strings, they tend to sound a bit dull (some say dead) right out of the package. But to me, they tend to feel smoother and sound better as they play in, while roundwounds tend to just get duller and wonkier as they age. With flatwound strings, I may change the plains periodically, but I tend keep the wound strings on virtually forever, unless I just want to change the style/gauges of the strings.

As to brands - I think there tends to be more difference in feel than sound among flatwounds. I like Thomastik and Pyramid for jazz, but D'Addario Chromes, GHS Precision Flatwound, DR Flatwounds, and others sound fine to me. Ernie Ball sometimes sets up at the Philly guitar show, and they did last fall. They had some boxes of 10-46 and 9-42 flatwounds - I had never tried them, but I got a couple of boxes of six of the 10-46. I put a set on my '68 Les Paul, and I think they sound and feel pretty good. I'm gonna up the gauge of strings 1-3 and 6 to 11, 14, 18, and 48/50 respectively to even out the tensions, but I think they will work out on some guitars that want lighter strings. I generally will mix/match flatwound string brands with no ill effect. As a couple of my guitar-playing friends stated, "Hell, Dave, they all sound dead to me.", LOL.

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Ditto on recommending Thomastik Swing flatwounds. If kept clean, the wounds do last for years. As for any of the stainless-wound strings, either flats or roundwounds will cause faster fret wear than nickelwounds.