New ethanol resistant GRP tanks for Norton?

Just noticed that Burton Bike Bits in the UK is able to supply all of the popular tanks for Norton Commando in GRP and that these have been properly tested, and found to be fully resistant to all pump fuels. Has anyone tried one of these I wonder, and if so was it sealed before use as suggested here: http://www.burtonbikebits.net/fibreglass%20tanks.pdf ?