Update: I took the M1934 outside, along with my TM Hi-Capa and KWA G18C, for some real cold weather testing at longer ranges.
The ambient temperature was 1C/34F, ammo was .20g Excel. Target was an A4 sheet of paper.
M1934: APS Winter gas. It couldn't reach the target at 20 meters, but at 15 meters it was no problem. Power consistency seemed very good, no cooldown. Firm blowback.
G18C: Green gas. After setting hop-up to max, the 18C could reach the target at 20 meters, but accuracy was terrible, it failed to actually hit the target. Power consistency was poor, with bad cooldown.
Hi-Capa: G