youthunter57,
I have the standard CS-24 with 10Watt TOA speaker. I had mine setup with the 15Watt TOA, but changed it back to the 10Watt, simply because it's more compact and I didn't seem to gain much with the 15W.
hammer007 hit it right. The SC-Pro is crazy loud, followed by the PB and then CS-24 (regular). I haevn't heard the Krakatoa, but can imagine it's a loud one. I haven't got my dosimeter yet, but will have some solid decibel readings on the various new callers shortly, dispelling any myths about what is or isn't the loudest caller(s).