Just as Karen C from Milbrae. stomach sleepers need very firm beds. Any arm or shoulder pain is not sign of the age as Karen thinks, but rather the result of soft mattress. It can be that springs are firm, but the pillow is too thick and soft. The result of the softness of the top causes your body to sink, but because you have more weight in your upper body then in your arms, your body sinks but arms do not and they are pushed back.
That results in pinched nerves and other serious conditions. Remember nerves do not regenerate.
Stomach sleepers must have firm mattress including the firm top. Otherwise serious medical problems. Mattress like Seally Carmel (discontinued by the company apparently they do not know what is good for the people) are firm and they have very little padding on top hence overall great for stomach sleepers. Perhaps the discontinuation of a solid mattress explains why Seally filled for Chapter 11. It would be good if teh new owner restarted production of this mattress.