The only problem I would have is if Felix turns out to be a monitor. That was probably destroy his character and all that good will he had from last season. Keep him the loyal confidant because of all the characters who had the development from the last season, other than all the ones Maslany played, of course, Felix showed the most and became an awesome character.
I wouldn't worry. It was clear that Dr. Leekie had no idea who Sarah was until she took over Beth's life. That wouldn't make any sense if Felix were her monitor.