The tops of the coils I've used have all been exactly level with the top of the 'posts', if I was going to change at all I'd probably try ever so slightly below the post tops, but not much more than 1-2mm and certainly not above. I've yet To try it with 2.5mm ID.
For me it's at least on a par with my duals but I guess some of that might be down to the juices I use, Malaysian, either creamy or fairly heavy on sweetener. With those this tank really brings out and concentrates the flavour, so much so that I had to switch out the Wotofo Clapton and am now using the 26+30 Clapton above.
I'd agree the build is staggeringly easy, I can do a complete build in just a few minutes with this, no drama and "Damn, what have I got wrong THIS time". If the Nudge is as good I'll likely use one of them just for citrus juices, get the flavour of lemon into a coil / wick and it's there forever, unlike creams and non-citrus fruits that I find I can chop and change with ease, with an almost instant flavour pick up from the Recurve. Love it.