It's completely crucial to have a fat wick through the coil, especially with lower VG juice. If you're not sure, you probably haven't put a thick enough wick through, imo at least.
For what it's worth all the boro tanks I've tried have chimneys which are too long, and degrade the flavour considerably (inhale especially) at 0.6ohms for what I vape.
That's an interesting thought, I've found my boros to have less flavour than my shorts RTAs as well. Wonder if the TMD boro will give equivalent amount of flavour to my rtas.