I just spent a couple of hours toying around with coils on the Reomizer 2 I just received. Short version: this is the perfect RBA for my VV Grand for me.
The A7 was an excellent performer on the VV Grand, I had a 2.0 ohm coil around some double-looped 1mm Ekowool for the last few days. Great clouds and flavor, but a bit too airy for me. If you like your vapes airy, I strongly suggest the A7.
For a tighter draw, The Reomizer 2 is a better fit. I tried one of the micro-coils, both with Kanthal 32g and Nichrome 1/64th ribbon, but the resistance was too low for my tastes. At 1.3 ohms, stuff just tastes a bit burnt to me at any voltage on any device. I do have some Kanthal 0.4mm ribbon and some 2mm Ekowool coming, both of which I purchased on Ebay, I might try another microcoil with that, but I doubt I can get the resistance I want with one of those.
With a double-looped Ekowool 1mm wick and 32g Kanthal looped 4/5, I get 2.1 ohms. I have found my sweet spot is 1.8-2.2 ohms, both on the VV Grand and on the Provari, using any RBA. The tightness of the draw is optimal. I do have to squonk a bit more often than with the A7. I tried flooding it a bit, which of course leads to gurgling until the excess liquid is vaporized, buta I can still vape through the flooding.
I might give the Ebaron Dripper Spiral a try in the future, but I seriously doubt I will improve my experience over the Reomizer 2.
Additional points: Compared to the A7, the shorter height makes for a more compact package. Building a coil is just as easy on both RBAs.