in the process of assembling a GP Super Sportster Arf. Should I use the supplied hinge "material"(like cloth strips)...or should I replace them with plastic hinges?

You'll get varying opinions on this subject, but IMO, good 'CA' hinges are safe, on this size plane, if installed properly and Great Planes includes serviceable hinge material with their kits. This is what I do after test fitting everything.

1. I drill a 1/16" hole in the center of each slot to facilitate the wicking process.
2. install a pin in the center line of each hinge (this insures that it will be centered in the slot with half in each surface)
3. install the hinges and slide the surfaces together
4. start on the bottom side, bend the joint slightly, and drop 3 or 4 drops of thin CA on each hinge (NO KICKER)
5. flip over and repeat step 4 (in this case, more glue is not better)
6. check for excess CA and clean with CA remover as needed (the 3 or 4 drops is enough to do the job but not so much the joint can't absorb it)
7. seal both sides of the hinge joint with strips of the appropriate color or clear covering

This all takes just a few minutes. Not bad.

I agree with ram3500. I will throw in my opinion that the best CA hinges are RadioSouth Pro hinges. I've had them in planes for years and never had one fail. I do agree that GP supplies good quality with their kits, however. No so true with other manufacturers.

I have used both but mainly use those CA hinges on anythng at 120 size or below. They're fine. Need to get super thin type CA for them.