I have a Unique and I love it!! There have been some that have developed gas leaks usually along the weld seams. The tank is very easy to pull and repair or replace should you choose to do so. Be sure to stop over at the Unique forums.
http://www.uniquecobra.com/forums/
Uniques are a fine Cobra and the Weavers are terrific folks! You can't go wrong with them!