Haven't tried the naturals but did have some bad
reviews?... I use the Kiwi at 4% with about 2% TFA sweetener; it's not super realistic but pleasant (some blends with it can get bitter though) with surprising throat hit (hints it can get too strong). I would try them alone first and then try dripping them together or otherwise mixed. Anything too strong can become almost unrecognizable but whether that's too strong depends on device.
Be sure to leave shake room in the bottle, a full bottle can't hardly be mixed. I find steeping (letting it sit, often for weeks) somewhat overrated but the first couple hours or day can make a big difference. The "burning up your coils" sounds like you may have other issues.