From what I can tell, the PL-350 seems to do a better job on MW than the
PL-550.

The PL-550 has incredibly rich sound for a portable, and it beats the PL-350
in that category.

I really loved the sound and feel of the PL-550, but 90% of my radio
listening is MW, so I sold the PL-550 to a friend and he is very happy with
it.

And since I no longer have the PL-550, then these comparisons are subject to
how well I can remember the PL-550. That means that it's probably a better
radio than I can remember.

Either way, I think your PL-550 is a very fine radio.