The only way the eliquid would be any different in thickness is if the pg/vg ratios were different. That said, it's okay to mix different ratios...it might just change the thickness a little if you use different ratios. (thinner has more pg, thicker has more vg). You should get more throat hit with more pg, and more vapor with vg. Personally, I like a 80/20 pg/vg for the throat hit, and still get enough vapor to keep me happy, but a 67/33 pg/vg works too!