The Shield is quite a bit smaller, but not as small as a PM9. I don't know how I could answer the question about concealing it except to say that I think if either gun is worn in a good belt holster the Shield will be less noticeable when covered with a thin shirt. If covering with a vest or jacket, I don't think it would make much difference on most guys. I don't regard either gun as suitable for pocket carry, but the Shield would come a lot closer than the 6906, IMHO.