I vape both ways-- mtl and dtl. The main difference in my mixes is the nicotine level. in my dtl mixes I try to not go lower that 70% VG. My mtl device can't handle anything higher in VG than a 65/35 blend, the tank simply won't feed properly with a higher VG ratio and will give me that occasional god awful dry hit.
If it wasn't for my tank I would probably do all my mixes in a 70/30 blend, that 30% pg level is a great flavor carrier. I also feel the steep times are less, but that could just be a mentality thing for me. Every time I have mixed something in high VG I always wonder-- "should I up the flavor in those mixes?".
I think the happy medium is 70/30 or even a 65/35 blend....