The only way that I will agree that an 11x5 will fly a trainer slower is if both are flying at full throttle. The only time you need anything close to full throttle on a trainer is for takeoff, climbing and if your in trouble. Other than that a trainer will putt around at half throttle or less for normal flying. If you want it to fly slower then back off the throttle. The plane isn't going to stall anytime sooner just because you using a lower/higher pitch prop. The LT40 will glide in at idle or deadstick no matter what prop so I don't see how it makes it easier to land.

When I said I'd bet an 11x7 would climb faster I'm not talking about straight up vertical, I mean flying level and giving it full throttle and letting it climb on it's own. Of course an 11x5 will pull better going straight up because it has more pulling power but again were talking about an LT40 and most people aren't looking for unlimited vertical on an LT40.