ORIGINAL: 2slow2matter
some planes will pitch nose down with flap deployment--not all planes pitch up. Also, flaps shouldn't increase tip stall--they should prevent it by makins sure the root stalls before the tip does. However, ailerons on the outter most portion of the wing (as opposed to strip ailerons) very well can cause tip stall if setup for flaperons, because you will indeed be inducing a stall out on the tip of the wing only.
as he was only mentioning flaperons, not real flaps, the tip still is a big issue... I run an obscene amount of flaperon/spoileron control on my ucando, and at full deflection it is borderline tip stall the entire time! (same with spoilerons)
as far as pitch up, two of my planes pitch up, two pitch down. I don't use flaps much on the ones that pitch down! it is really an uneasy feeling when you add some flaps and end up with the nose suddenly lower then it was before. (my 3d planes pitch up, the rest pitch down, don't know if that actually is just coincidence or not...)