I know that Cal 550 was used for NA version of SM300 due to it being easier/cheaper to import, since it had 17 jewels. Question I have is, does a vintage SM300 with cal 550 have same value as 552 would? For sake of argument, everything between the 2 watches is same, just movement is different. I would think 552 version would be a bit more expensive because that movement is considered better, but that is just my very uneducated guess.
Everything else equal, I would pay the same for those two watches. A 550 in good condition is good enough.