I've been a serial GAS addict for many years: I don't even know if that qualifies as truly gear acquisition syndrome, as I usually had to sell one camera or lens to get another. For a while, in my twenties, I had the most gear: two Canon F1's, a Leica, several Canon primes, a zoom, and two Leitz lenses. But I never, ever lugged it all around. I'd take out a body and a lens, or two lenses. Perhaps it was memories of dragging newspaper bags around when I delivered the morning and evening papers as a teen, whatever, I never liked having all that gear, and psychologically it weighed on me as much if not more than the actual weight of all that glass. So I sold it. And began a crazy buy one-sell it-buy another theme that has gone on for years: from one make to another, 35 to 120 back to 35. There were, sometimes, extenuating circumstances which forced me to sell: tuition needed, a major car repair, etc. Other times, I got bored with the camera or lens or both. I think my happiest times were when I had a new Konica Hexar with the silent mode and had no choice but to compose for a 35mm lens.
Actually, even when I've had more gear, I've enjoyed going out with one camera and one lens, and just seeing with that lens in mind. Some days it might be a telephoto, and if a wide-angle shot presented itself, I had to think: How can I do this with a 90mm? Of course, if you're out with a wider lens, and shoot something that would have been better shot with a longer lens, you can blow up the image, the perspective remains the same so other than grain you get with blowing up, you are carrying, in effect, a longer lens whenever you use a 35 or 40 or 50...
I now have only this: a Bessa R3M, the 35/1.7 and the 50/1.5 Voigtlander lenses. No doubt I'll sell the body in due course...