The plastic strips are a low-cost (unless you intend to retrofit an existing trailer - then the price gets you) alternative to rollers when used with hard hulls. Low friction, so the boat slides off and on easier than carpet.
On another forum, there were quite a few posts about boats prematurely leaving the trailer after the mod was installed. Some reports of scuffing and wear as well.
On a SIB, I'm not sure it's necessary, as generally you don't (well, I didn't) want to drag the boat along the trailer much; better to float the boat into position as much as possible and raise the trailer under the boat as you pull it out.
But I doubt it will cause any problems compared to carpet. You will see your bunk covering lasting longer, I'm sure. Make sure that the edges are rounded off (if not take a router and a roundover bit to them) and the screws are well recessed (assuming they're fastened from the top down.)