The dies don't dull - not in your lifetime anyway - and by then it would of paid for itself by then ... I would not recommend cutting foil something about that sounds bad to me.. I've never done it and I've had my go and dies for at least five years now.. And yes I can say I do use them very often.. Not a week goes by without me pulling out a die or two or three.
Change your mat often. Move them over so the die does not cut in the same exact spot every time .. You do not need to cover the entire die with your mat just over the blades ... Flip and turn your mats after every pass through. And invest in back-up mats . They are not expensive, and worth not having the added stress your having now ..
Dont toss the mat you have been using but use for another die... I have multiple mats to use at any given time .. When one isn't cutting smoothly I grab another till it works out..
Remember don't toss out the UN- usable mats instead repurpose for tote bottoms .
My GO is the best investment hubby has ever made for me ... So much so, that I have two ...