No Rudders, no problem.....but splitting the elevons into independent elevators and ailerons will be a problem on the Roo.
Lots of deltas like the Eurofighter and Rafale do it, but you need canards and washout in the wing.

On our Roos, if you split off the ailerons with no mix, you definitely will not have enough pitch authority for takeoff and landing. It needs all it can get as it is currently designed. They take-off and fly nose heavy due to fuel in front of the C.G. Additionally, by cranking in all that up elevator with neutral ailerons in the landing flare, you are asking for a snap, since the AOA of the inboard wing will be significantly less than the outboard, the opposite of washout.

Redundancy is great, but rarely needed. My buddy has over 100 flights on his foam wing Roo-I with one 8411, and I have over 100 flights on my HS, also with one 8411/side with absolutely zero problems. Just finishing up a new foam wing Roo for 3-D stuff and it also will have one 8411/side.

Just Y the elevons together. 8411's are fine but overkill with 2/side. 70oz servos would be enough, IMO. I flew my first HS with single 4131 and then an 8231/side for over 100 flights with no problems.

Tom