Firstly, no-one is THAT interested in your hair to be looking out for something like a lace edge or knots.
You see someone with hair and if it suits the person wearing it, you just accept that its a natural head of hair.
Its only another wearer that specifically goes around studying and inspecting.

But, regarding the hairline, its perfectly possible to wear hair off the face and still use odd stray hairs to fall forward and cover any edge (skin or lace system) if it makes the wearer more comfortable and less self conscious.
You just take the very front line of hairs along the hairline and run a razor comb through them to create some fine 'baby-like' hairs that fall forward and independent of the longer hairs behind them, that you sweep back.
You see this on many natural heads of hair and its just enough to disguise or break-up any line or edge you're worrying about.
A bit like this guy has along his hairline:
http://i1202.photobucket.com/albums/bb37...13f497.jpg
or this:
http://inyourface.blog.ocregister.com/fi...0715-2.jpg


You can also use a comb & a hairdrier to bring the hair slightly forward, before then taking it back off your forehead.
This creates a shadow along the hairline and a slight 'fake' hairline where there are no base edges or knots visible.
Like this:
http://i1202.photobucket.com/albums/bb37...2d5028.jpg

The red line indicates where the actual base edge is.