I just did a ZFM mod on my No. 7 Stealth E-Cig. It uses a resivoir instead of the pollyfill. I'd imagine that since it's a resivoir instead of a "sponge" you could just wash out the resivoir, drip your flavor, try it, then wash it out again if you don't like it and switch back to your original. The residual liquid that is left on the atomizer might take a little while to vaporize away, but I would guess you'll be back to your original tasting liquid in no time. I'll test it out and let you know.