I too analyzed the options and chose Vortex. I felt the marginal difference in efficiency ratings were inconsequential, and thus let warranty and design drive the decision. Despite the purchase being made 4 years ago, Vortex panels weighed more than its competitors. I had one panel leak, just last month, and they promptly sent a replacement.

The Goldline electronics work fantastic, and capture solar gain whenever it's possible. I'm in the process of researching a smaller .5hp pump that will be plumbed exclusively for the solar.