It looks like the issue you're seeing is simply due to how ADSL tends to be adaptive to changes in the line condition. At least as it stands right now, you're right at the edge, if not, slightly past the typical range for the 10Mbps speed so your line will more than likely sync at different rates on every reboot. The last time your modem held the 11Mbps sync rate (if that is what you mentioned above) was probably at a time when the line had more capacity to deliver the speed. As of right now, your noise margins are below the suggested values, so your line will most likely become unstable if additional noise is added to the line or if conditions deteriorate, but it is still above the threshold of not being able to hold sync at your current speed.
If you have access to a NID, you can try plugging your modem into it if possible to rule out your home wiring causing any issues with the DSL. If the statistics don't improve, you can try getting Verizon to send a tech out. Otherwise, I wouldn't bother hassling with the tech support a whole lot as from past experience with helping others, the speed usually winds up going down even more (sometimes to the slowest package, which trust me, is a huge slowdown).
If you need info on what a NID is, view this page: http://www.dslreports.com/faq/1317
