Hey Ahmet, thanks for all the great work!
The particles (Octane ObjectTag) in x-particles don't scale via Particle Scale parameter, only via Particle Radius. Because of it, there's much less what we can do about them. i.e. we can't scale them only in one axis.
Right now I'm looking for a workaround
If you'd like to improve on x-particles integration, just let me know. We can help and test