Yea the SP is for moderaty severe to severe and the UP is really for severe to profound. The SP will go down to profound level but you really start to max the aid out which means it wont sound as good.
The UP takes a 675 and the SP takes a 13 battery.
Size different between the SP and UP is TINY!
A lot of people who have gone from the SP to the UP say the UP sounds a lot better.
