I have an old jazz archtop fitted with D'addario chromes - strings I haven't changed for years - and kept good with the occasional fast-fret application. I also have a now rare Yamaha AEX 500 jazz thinbody which plays beautifully but no matter what round wound strings I use, there's always that annoying string screech, especially when you're changing chord every half bar. The guitar construction is such that it doesn't suit heavier strings and so I decided to invest in the lightest gauge of D'addario chromes (010 on the first string) and see what improvement it gave. Voila! The screech is gone and the lighter strings don't overburden the guitar affecting set up and tuning. Also, the tonal balance is better and in the case of this particular guitar (a bridge piezo and a neck mini-humbucker), a sweetness on the lower strings that I couldn't get with the round-wounds. I tend to play classic, Great American Songbook type jazz through an acoustic amp and these string suit the style, the guitar and the player down to the ground.