The Linn felt mat sucks. I also have tried many of the available mats made for the LP12. While it is true that most offer no sonic advantage other than sparing one from the annoying static issue plus the unsightlyness, the Plattamat 2 from Analogue Innovation is a sonic improvement. The Plattamat 2 is a rubber cork blend tailored for the LP12. It looks better also.
http://www.analogueinnovation.com/page6.htm
http://www.analogueinnovation.com/page6.htm