hmm... haven't had to deal w/this yet - but other than burning/scarring the new liner you have (easy to patch w/new) I would seriously recommend having a few mount tabs at least brazed (preferably welded) on the underside of the tank.
It'd be cheap enough as it'd only take a minute if you had the tabs all made up and the tank prepped (sanded clean where the tabs go). I would never
trust double sided tape for that job, particularly as gasoline is such a fine solvent for that type adhesive. Sooner or later you'd spill fuel and run the risk of loosing yer tank at speed o_O
The double sided foam tape is much better used in conjunction with proper mounts - to reduce movement/noise, that might be what you read about. I wouldn't just tape ANYTHING to my bike and expect it to stay lol and the fuel tank is somewhat important