Given full D3 warranty: When my D1 went south, I called and they sent me a D2 to replace it. That worked great and when IT went south, another D2 was excellent. Wife and I both have D3 - mine is locking, rebooting, and trudging slowly so much I am calling it in for warranty this week. Has anyone that called a warranty D3 had a D4 as an option or do you have other advise? I absolutely need GPS to work, not an option! Thanks for ANY advice!