When 'S' first showed up I was entranced... at 20wpm it was this lovely, brief dih-dih-dih in your ears. A quick, little kiss, her answer, breathed into your ear. I loved it! Alas. As the characters slowly entered the ballroom - I've now learned about half of them - I quickly found that my lovely, little 'S' wasn't quite so unique after all. 'H' and '4' and '5' and 'i' all sought to steal some of her limelight. And as if that wasn't bad enough, I quickly found it even worse when they tried to dance together, their sibilant notes blending into a discordant mess. Context helps with regular words, of course. But not so much with call signs. Ergo my question... in the context of vanity calls - where one can obviously choose one's cast of characters - are adjacent combinations of these bunches-of-dits characters troublesome in CW? I'm in 4-land (and am both proud and happy to retain the '4' which tells people that). The prefix of K or W or N isn't a problem. But I'm wondering if following that '4' with, say, an 'S' or an 'H' might be a problem? Especially out in the real world where QRP operation gives a starting handicap, and then gets laced with QRM and QRN and QRQ and the vagaries of operators' fists and plain out-and-out sending errors?