The 10x8 will put roughly the same engine load as a 11x6, BUT the 10x8 is going to fly the plane a lot faster with less thrust. The 11x6 would have more thrust with a little less speed on top end. A 10x9 would have the same load as a 11x7. A 12x5 or 12x4 would give you even more thrust with a little less top end. Trainers are not designed to go fast anyway, so I always recommend to my students to get more thrust than speed right now. More thrust can get you out of trouble if you need it. A 10" prop is too small for a 46 unless you are looking for speed, which I would think a person on a trainer is not looking for when learning and/or developing his or her skills. More thrust will lift the plane off the ground faster and the bigger prop with lower pitch will have more braking affect on the landing approach which really helps new pilots.