Do I possibly have a "defective" unit? possibly. The beam certainly is not the same as the other T10xx lights. When I first saw the beam, I immediately thought that something was wrong.
FWIW, after a few battery discharges (AW, Ultrafire) in the T10L, I just now compared the T10L beam to the 6 other Eagletac lights - T-series and P-series. The T10L certainly has rings, even more so than with the P-series lights. The other T-series lights possess a smooth transition from spot to spill. The T10L has a ringy beam. However, when in use, and especially outside, the rings are not noticeable.
Also, the reverse-voltage "bumpers" fell off from the PC board in the head. These are the "bumpers" that would prevent the application of a reversed voltage on the light head because of a cell inserted backwards.