I've been vaping nothing but a DNA40 device since I got it 100% of the time using nickel wire and temp. My biggest attraction to temp control is the flavor and not inhaling torched juices & wick - which ultimately makes the flavor nastier, obviously, but also carries potential health risks.
As far as difference between the flavor of nickel vs kanthal, I don't get any funky taste off of nickel. I think whether a freshly wrapped coil from kanthal or nickel, the first few puffs are a bit weird but nothing significant and it fades quickly, then its shear bliss.
My kanthal DNA30 set ups would get gunked up after a few tanks. Not because I ever vaped sub-ohms or pumped the watts higher then 12, but because I like thicker sweet juices. With my DNA40 set to 410 degrees, I find it gunks up about half as fast. Now that I've got the hang of wrapping nickel wire coils, it takes no time and is a breeze. I wont ever dry burn a nickel coil, however, like I did with kanthal all the time to clean it, so instead I try to wipe it off with paper towel and clean wicks to wipe of the inside of the coils, but if its too gunked, I just re-wrap a coil in 2-5 mins and am back to perfection for a few more days. I get great vapor and flavor without torching anything and am extremely impressed.
Yeah, there have been issues with DNA40 boards, but evolv is good about rectifying any issues. I also can't access the nextgen website using a mac & safari. With the DNA 20 & 30 boards, I'd be willing to bet that issues with the futura were not the evolv boards, but something else.