used PC3 fins (all I had spare) it is a little Dynamo! pivots and whips around all over the place in one word FUN!
As for the comparison to the El Fuego - I think a 5'8" Potatonator will cross over too much in the lower end of waves with the 5"11 El Fuego. If you are looking to add another board to the quiver for the mushiest of days I'd probably go a Sweet Potato - unless you want a seemless changeover board to board by this I mean not having to change your surfing style between boards
One thing I liked about the sweet potato was how I had to surf it completely different than my other boards - for me this kept things fresh