So overall do you recommend it? I was debating between this GLA one and the Aquatek mini regulator for paintball.
Yes, I would definitely recommend it. It's the only CO2 regulator I have ever had, so I don't know how it compares to the Aquatek.
And can the GLA atomic reg be used with a standard glass/ceramic diffuser or does it need to be an atomic diffuser?
I use it with an atomic diffuser, so I don't know if it can be used with a standard glass/ceramic one.