It took me a while to upload this because i lost my phone sync cable and had to upload them from my phone instead. But I just got SFxT today and had the gems via the PSN slip up on first day of cross assault.
Anyway, DLC gems seem to be the same as regular gems WITHOUT the negative. so there is no reason to not use them. The issue being paying to be stronger than other players which i don’t agree with.
Link to gallery with images
Also i just noticed the first image uploaded wrong. It’s the same as the second image but without the negative of damage loss.