Panasonic 25m f1.4 light transmission test

Hi all,

Need some help here. I have the EM1 and the two pro zooms and i need a faster lens for indoor shooting in the normal focal range. I am not very fond of primes because i don't like the ideia of being stuck in a focal distance, but as i never had any, i can't really tell if i'm going to like it or not. In any case i need extra speed so i have to go with a prime and i am considering the Panasonic 25m f1.4

I would like to ask if anybody has both the Pana 25m 1.4 and the Olympus 25m 1.8 and can compare if the gain in speed from the 1.8 to the 1.4 (two thirds of stop) really shows in the shutter speed when shooting the same scene. Or, anyone that has the 12-40 2.8 and the Pana 25 can test their two stops difference. I'm going here for the gain in the shutter speed, not so much on blur capacity, although it is nice to have it too.

The reason i ask this is because i read somewhere that the Pana might not really be an f1.4 in light transmission but more of an f1.7 or f1.8, and the Oly an f2.0. I know it is normal for any lens to lose 1/3 of stop relative to the announced fnumber, but if the pana loses 1/2 a stop instead of 1/3, it might be a little to much to justify the purchase.

Thanks in advance for the help.