What is the difference in the Excalibur models other than the coil size on the 800 and the 1000? As far as I can tell, there is three models of the Excalibur, the Excalibur, Excalibur 800, and Excalibur 1000. Other than the battery style on the older model, is it the same as the newer ones? Is the Excalibur 800 & 1000 the same machine just 8" & 10" coils? Just curious, I would like to pick one up, preferably a used one in the future but don't want to buy the wrong one.