I have two Finnex's on a Medusa (believe they are 100 or 150w each), with a backup 50w WON set much lower (been lucky so far apparently).
Those of you with a controller, do you have the Finnex titanium heating tube only with no controls? I bought my Finnex's before my controller (they just have the dial knob), but am thinking about swapping them out (can use these for QT, backup, and such). This is my first winter with the additional 180 gallons, and probably need to do a bump just in case.