n2 is a beast. Can't argue with a 4" coil though. Thing about 4" coil subs though is the soft parts still have to hold up. Personally, if I have to be limited by one or the other, I'd rather be limited mechanically because you can hear the sub getting into trouble. If you're taxing it thermally, by the time you smell it (if you do), it may be hurt already.
With that said, love both subs and if I had 3k to give one of them, I might lean toward the Treo. That is... unless you want to buy my N2 //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif