I love metal for the same reasons as you, and that they have fine scale tread available (you can't get that from plastic, that I know of...). I used to use P2K, but I've since switched to Branchline for 33" & 36" and NWSL for 28" and 38". I decided to use code 88 (fine scale HO) tread on all new items, however I will not spend the extra cash, yet, to switch items that already have code 110 metal wheels.
I have also noticed the metal wheels picking, however I no longer have this issue with properly weighted items.