If you do a search on of the forums and use the word MYLAR you will find several threads over the year where this has been discussed.
Thread #112887 - 09/17/06 02:59 PM and another
Thread #115387 - 10/25/06 08:08 PM
(I have no idea how to link to a thread or I would do it. MODERATORS - Perhaps we should put these posts on the Beginner board since they seem to come up every year)

Back to Blazer's original question about super ultra light (SUL)
Here's a thread - #112887 - 09/17/06 02:59 PM
#131691 - 06/14/07 01:25 AM
also do a search for ANDREW SKURKA or RYAN JORDAN
or google them. These guys are on the leading edge of ultralite (and sometimes pay the consequences)

Most folks here go light weight, but not SUL.

But whatever floats your boat (oh wait, that's another topic <img src="/forums/images/graemlins/smile.gif" alt="" /> )