I think I can give you an answer...
I have a 1999 Hunter 380 with the firberglass arch. For some years I wanted an arch and even designed one for my H 35.5 but I never got it made.I believe Hunter switched to the stainless for several reasons, 1) buyers wanted stairless--they didn't like the looks of the fiberglass, 2) it was cheaper to build the stainless arch, particularly in the hull section, and 3) the stainless arch was easier to leave off if the buyer didn't want it. How much of this is absolutely fact, I cannot attest to.At first, I wasn't sure I liked the looks of the firberglass arch but have come to love it. It has been a blessing in many ways. We really like the two lights that are installed in the arch--I'm surprised how many times I've used them. I hung my radar display from the arch which is perfect for the helmsperson. Our rain fly is attached fore and aft on the arch--easier to do than on the stainless. I attached the MOB bag to the outside of the arch; still easy to get at, but out of the way. And the fiberglass arch is nicer to snuggle up to when in a blow. Nice back support. And, yes, I now think the looks are quite good--it balances the boat out when viewed from the beam. You asked if there was a con--I think the stern two mooring cleats are harder to get at when docking. We now leave mooring lines attached on each side and hung on a plastic straps when not in use but ready to go. Other than that, I can't think of any other negatives to the fiberglass arch.I'm thinking of getting Hunter to send me two of their new logos and attaching them to the outside of the arch. A bit of class, eh?Les