Yes, it makes hovering much more easy to control. I think it because low pitch propeller is more effecient at low speeds and gives better airstream to aileron roots and tail feathers. When you hover, the airstream more or less spirals down the fuselage. Low pitch makes the spiral straighter. This is my theory -- do you agree?

APC makes 15x4W that has wide blades. They also have 16x4W. This might be too much for 91 4-stroke but OS 91 FX turns it easily.

Currently I use 14x4W in Irvine 72 (Diablotin) and Saito 72 (Laser 3D). When you go to smaller models look at 13x4W (for YS 63 & 60-2-strokes) and 13x4 (for Irvine 53 & Rossi 53). I have found that the 46-size 2-strokes can use APC 12,25x3,75, 12x4 or 11,5x4.