We went with MainSails recommendation for Solbian spring of 2014. AND VERRY HAPPY WITH OUR PURCHASE.
Two panels Bimini mounted. Our sailmaker recommended the Velcro flap only on the fwd and aft (long) edges. He felt leaving the short sides open would be better for allowing any water to drain out and reduce mold growth under the panels.
Sailed NE 2014 summer and to Fla fall/winter and NE all 2015 and 16 summer. Never a problem.
As Main has stated shadow from boom greatly reduces output. - Our boom extends over part of the bimini so we had to make sure it was tied to keep shadow off when we were moored/anchored.