What is the "sound" dif. between a Joule -Elctra OTL and a SET amp??

Guys- I currently have the Wyetech Topaz 211 with KR 211 tubes and audio note transformers which I love - BUT have always been intrigued by the Joule Elctra OTL's at past shows- I have been offered by a dealer a pair of VZN-100's not sure if they are MK IV or V or what the difference between the 2 versions are but was wondering from a sound presentation between my 211 SET amps and the OTL- I am using the Classic Audio T1.4 horn speakers- Thanks so much for the opinions as always!!