The clanky-ness of brand new rounds annoys me to the point that I find myself unable to play newly strung basses in music stores to try out other pieces of gearI agree that broken-in rounds aren't the best options for slapping, but in the context of what I play, I'm not really required to slap, so it works out for me.
I'm right there with ya. It can be quite frustrating when the sound of just about every bass hanging on the wall is unappealing to you cause they've all got fresh rounds.
Personally, new rounds only ever sounded good to me when I was a kid playing punk with a pick, or when I slapped. They just don't sound like a bass to me with all that zingy top end, plus the noise from shifting positions, the clanking, etc. Nickels aren't as bad fresh, so I use those as I can actually bear them as they break in.
I'll never understand why fresh rounds are so popular, dead ones are the way to go if you want smooth, clear tone IMO