Here's what surprised me a little at first - when I thought "somethings wrong with the flavor" on my ProTank, vaping at 8 watts, compared to the same juice in an EVOD. Yes, there's a slight difference in draw, etc - but REALLY what I had figured was that there is a TASTE difference between different resistance coils - EVEN IF YOU'RE USING VW.
I had kind of assumed that having set watts instead of voltage would make it so any resistance would work - but nope, I have a preference for a coil thats 1.5-2.0. Higher, and I lose something. I'm sure there are other folks for whom it's the opposite, choosing 3 ohm coils becuase it effects their vape.
Thank you for posting this, I honestly had noticed something similar but had always assumed it was my mind playing tricks on me..I think more people need to be aware of this phenomenon. I mean I never even considered it as for a while I had a Vamo with VW and did the same as you, 7 watts, no matter the head I used it should taste the same, but it didn't. Just chalked it up to my taste buds, but if someone else can back it up, it seems like it is the heads. Not had any trouble since I started making my own though, knock on wood.