My wife and I are looking at Sunrise replacement windows. They seem to be very sturdy windows with a nice lifetime warranty. I've heard that I definitely want to get some kind of structurally reinforced vinyl window as vinyl by itself is not very strong. In looking at how these windows are reinforced, the best I've come up with is this statement:
FiberCore Plus, a pultruded fiberglass I-beam reinforcement that is coupled with urethane insulation comes with every door to add to the strength of the design.
(from here)
How does Fiberglass compare to aluminum/steel reinforcement structurally? Is fiberglass reinforcement sufficient/superior/worse? Should I be concerned with fiberglass reinforcement in any way? How will the reinforcement material impact the window's lifespan?
Note, I'm in the Mid Atlantic (Maryland).