I also see this issue, but with upload speeds only. They can test ok to the nearest Verizon server, but when actually sending or uploading, the actual speed is often only about 1% of the promised speed. Up until recently, actual upload speed was very good, perhaps 50-60% of stated speed.
After multiple service visits and all home FIOS equipment and wiring changed, I still can't ever achieve more than a 1Meg actual upload speed even though I pay for 25 Meg upload speed. Actual upload speeds are usually 300 kbps or slower when using most of the major file sharing or online storage services or websites. Verizon will not acknowledge or attempt to fix the issue if it tests fine to their local server using their speed testing web page.
Something has changed in their network recently in the way that it deals with uploads from FIOS customers.
Please see my thread here:
http://forums.verizon.com/t5/FiOS-Internet/Slow-real-world-upload-speed/td-p/654849