Composite Kangaroo
Johnny, I bought one of the composite Kangaroo's at Florida jets as well and Don and Mark at Planes Plus both recommended using 4-8411's for the elevons. I don't know if it is required but that is what they recommended to me. I am using 4 myself.
I don't want to find out the hard way that I should have used 4 instead of two. Like JackJet said it's worth the extra money.
Just so you know, if you call Planes Plus you can probably get the 8411's for about that same price. I bought 8 of them recently for $100.00 each I think.
They have them by the boat load because they setup Giant scale planes which are ganged and require testing a number of servos to get them to match. Gary Jefferson