Two M22s arranged in a horizontal fashion are $62 more than a VP150. If you plan on frequently listening to the centre 10 to 30 degrees off-axis, I would highly recommend two horizontal M22s. If not, go with the 150.
Two M22s as fronts are more than adequate for your room size. Know however that if you get M80s, you will have more amp headroom. The M22s are about half as sensitive as the M80s so you will need twice the amplifier power into the M22s as the M80s to achieve the same sound pressure level.
