As an avid fan of down-tuned music in general, these strings have intrigued me for quite a while. With the strings I normally use (EXL157) for my A# tuning, I can't go that much lower without sacrificing the tone and playability of the instrument. With these strings I managed to actually tune a standard scale guitar to E2 (one octave down from standard E), mind you though a lot of adjustments had to be done to the neck. But it intonated really well and sounded really evil. I wouldn't recommend using these on a standard scale guitar though, they're just to thick really.
This was more of a fun project just to see if it's possible, and yes it is! I couldn't imagine these strings would ever break or snap, D'Addario strings in general really don't break that much, I can't even remeber the last time a string failed on me. However, the day these will snap, I wouldn't want to stand anyway near that instrument.