I've had all three..but sold the exp II to get a SE.....So now I still have the XS and the SE..when turning on each the XS was the slowest to go thur the startup screen...the SE, and the EXP II were much faster.., therefore faster machines, on targets Plus I can not use the XS anymore because I've got use to the hunting AllMetal, Ferrious Tones..then watching the digital read out...The SE and the Exp II have Digital display that shows both the ferrous content (FER) and the conductivity (COND), where as the XS has Digital mode depicts target ID with a numerical value ranging from 1 to 32 (FER) and a corresponding picture icon; i.e., coin, nail, pull tab, etc There are a few other differences but mostly all three are brothers sharing many of the same features, each upgrade the machine has become faster..Different Processors? With a few improvements on each.................................Once you go forwards, it hard to go back...