If you're comfortable with it being a private company that has proprietary software and utilizes a CLA for its own components, then by all means, use them.

Personally I'm at a point where I distrust any essential software that isn't GPL licensed, as that's the only way to ensure that it'll always be in the community's hands. Otherwise, we're just hedging that Sailfish won't someday be sold to a larger publicly traded company, who will then utilize the potential lock-in factor that the proprietary parts of Sailfish and the CLA'd components bring.

PMOS is certainly not in a usable state for the average person yet, which is why I suggest people donate to it so it can become more polished and support more phones.