I have a set of them as well. They sound great, but can't tolerate them for extended periods.
Although I haven't contracted an infection from using them, my ear canals do get irritated because moisture builds up inside.
I tried the different ear pieces and preferred the ones pictured; they seemed to sound the best.
The other types just did not appeal to me for one reason or another.
Nevertheless, I certainly wouldn't use these while on the beach in the hot sun.