Hi,
I have been using scalp protector and find it worthwhile.I get less skin irritation,and tapes stick to it really well.

I can't comment on knot sealer as i have not used it on a lace system,i replace my systems regular before shedding becomes a problem.I am also concerned that if you lock the knots in position with knot sealer,the hairs will not move around and style as easily(i have free style units) just my opinion.

Regards Topcat