Sanyo HIT or Suntech panels worth the money?

We are narrowing down the selection process for getting a grid tied solar system, and have gotten several bids for systems. We are in Northern California, but far enough inland that temperatures can get up to 90-100 F, but we can get cloudier foggier weather in the winter. We've gotten a bid for a 6.7 (AC) Kw system with SMA inverter and REC panels for $53,000, or a 6.5 (AC) system with same inverter but with Sanyo HIT panels for $56,000. We also got a bid for a 6.7 kw system Sunpower panels for $57,000. After rebates and tax credits the total installed cost would range from around $30,000-$33,000, but of course the system with the Sanyo panels is slightly smaller. Both the companies we are looking at have excellent reputations and have been in the business for a long time, and don't subcontract the work, so I would feel fine with either one doing the installation. The big question is whether there would be any substantial benefit either in high heat or shady days to either the Sanyo or the Suntech panels, or whether we should just go with the REC panels based on price? Sanyo has now upgraded their warranty to 5 years for materials and workmanship, but the power performance warranty is slightly better for Sunpower and the REC panels.