Based on the 100s of people running 1500s and 3000s at 1/2 ohm -- you are unlikely to have an issue. Even though you aren't covered by the free replacement warranty you do have this:
http://www.sundownaudio.com/warranty.html
"1) If your amplifier has a blown power supply or damage from excessive vibration there will be a charge for a warranty replacement within the 2-year policy:
* SAZ-1500D and smaller amplifiers (or any future model under 2000 watts) - $30 in the continental USA (AK and HI add $15)
* SAZ-2000D and SAZ-3000D (or any future model 2000 - 3000 watts) - $50 in the continental USA (AK and HI add $20)"
So for 50 bucks you can get the amp replaced assuming it is not beat all to heck -- it is pro-rated a bit if the amp looks like it was dragged behind your car //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif
You will get over 2000 watts at 1/2 ohm //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif Derrick and Gary on Team Sundown have been testing it for months so I'm sure they would be willing to share their results.
PS: Not sure if you saw my above... but we are working on a 2 ohm amp -- nothing regulated for multiple loads like the JL, though.