when talking the 42 rads, you have to accept that some paneristis will say they are too small and not true to the heritage/DNA of the brand. as such, re-sale might not be as strong as some other options in the line up.
to me, the 42 rads are nice for a more discrete option and for those with smaller wrists. i also really like the dial's font. regarding jackson's comment above about the size, i haven't tried the 42s on, but, i remember when i first got into panerai, i tried on the 40mm luminors and quickly realized that 40 was too small for the brand, and 44 was better (for me).
as for 337 vs 338, it's a tough call. i like the gold hand of the 338, but i think i prefer the brightness of SS.
you could also consider the new 1940s rads. same 42mm size and same in-house P.999 movement with 60 hour power reserve, but a little more presence thanks to the lugs. for me, the 512 would be perfect if it didn't have the fake patina. if you like the dirty lume, however, it's a great option.
