Hi garaboy.... Poly would likely be too visible at the front due to the graduated density and the eventual normal shedding which most systems go through... I always wore poly sides/back on my toppers-- An inch width ,but 3/4s of an inch would be fine too...most tapes are 3/4s of an inch width too so , worth bearing that in mind. Just have a lace-front.
Also, removal of your system is slightly different when you have a poly strip as opposed to an all-lace. Poly is obviously impervious to liquids, so spraying lace-release `down`on to it, will not result in de-bond..... an easy way is spray a little lace-release on at the point where the lace joins the poly... it will tend to seep in there and help release the hold of the tape and/or glue.
Release your lace front as normal, then fold it up/back until you can see the `start`of the poly...spray a little lace-release on there, taking care to avoid your eyes, then wait a minute for it to work, then gently peel the system back further until you meet `resistance`..spray on more, wait , and `peel back` further ...you`ll have it released easily that way..... advantages of poly is it`s robust and easily cleaned..also very easy to `take`to tapes and glues when re-bonding. Disadvantages can be, slightly more detectable to touch at the edge, especially with tape under it, as the tape is marginally thicker than glue.... also some guys assert that because hair is either injected or looped into poly and hand-tied onto lace, the end-result can be a bit `off` because the hair lies differently on the 2 materials.....it`s never been an issue that I noticed. It`s easy to maybe tend to `over-analyse` or `worry` about every little detail..... just go for your choice [poly/lace combination] and see how you find it...you can tweak your next order as you see fit.....cheers.