I'm also running an Pico with a Cubis tank, fantastic little mod for what I need (MTL, fits in your hand, slick grey colour).
My first batteries were efest 3000mah (it was only later I came across Mooch and his wise advice).
Recently bought HG2s (from a reputable source) but my XTAR VC2 is only showing 2200mah capacity on both cells - and they definitely underperform vs. the efest. About 25% less vaping time, XTAR showing about 25% less capacity than advertised.
Assuming they're either fake, or faulty. But I've got some Samsung 30Q coming today so will let you know my thoughts.