From my own experience with the product, I can say the fiberglass definitely increases the strength, but I wouldn't necessarily remove the wire or rebar, although I'd be comfortable reducing the amount. I poured my driveway in Hawaii, which has very unstable soil, using reinforced concrete, albeit a 5000 psi mix. 10 years later, it's still the ONLY driveway on the street that has no cracking whatsoever, except at the control joints. The glass fibers in concrete are very similar to what you would find in 5/8 fire rated drywall. And that's STRONG stuff !!! I'd still want the added assurance of mesh and rebar, in the event a crack did occur, to hold the concrete together.