You know, if I were one country, having a cold war with another, I'd adopt the calibers of ammunition THEY used (unless they were completely unsuitable to my uses). That way, I could acutally USE captured ammo depots.
Therefore, if I had been the Russians, I would've switched to 9x19 for a pistol cartridge, and 5.56 instead of making my own cartridge, the 5.45mm. That's just me, though.
One argument against adopting the "enemies" chosen munitions for standard issue is to avoid
your own captured ammunition from readily being used against
you.
As for Russia switching to the 9x19 during the cold war, that could only have happened towards the latter era, since the .45acp in 1911 format was our standard sidearm up until '84.
For some reason, I just can't imagine the Russians adopting a .45 caliber handgun.
As for the switch from the 7.62x25 to the 9x18, I scratch my head on that one too... perhaps because it could be had in a more compact sidearm? That's a good question.
One thing I do know is that the 7.62x25 was feed reliable and at 1600 fps, possessed some decent stopping power as well.
Back to your questions on effectiveness; have you looked into the Russian made "SilverBear" ammuntion? Granted, it's not a typical load for the Makarov, but it was made specifically for it by LVE. If you already have a Makarov with 9x18 barrel, you might be able to make do with these until you decide on which 9x19 to carry.
After firing 70 or so rounds (before I became convinced a stouter $7 Wolff 19lb recoil spring was needed), I became impressed with the reliability and particularly the accuracy of the ammunition.
It still utilizes the berdan-primed steel case, but these are nickel plated... and the 120gr JHP bullet with huge gaping maw expand even after first punching through 4 layers of denim.
Once I get the recoil spring replacement, I will throw this puppy in the car's lock-box and have no worries.