I've got a SynMat Basic 7.5. A simpler mat than yours, without the pump & lighter.
Have had it for at least 3 years now, have used it for at least 150 nights, maybe even close to 200.
Best mat ever! Very comfy, simple, light, cheap, warm enuf for what I do ... which occasionally includes frosty & snowy nights snowy nights in Tassie Moutains and Vic/NSW alps.

I blow it up by mouth ... ie. must be some moisture getting in ... and store it with valve open 3 times folded lengthwise in a shelf.
No issues so far.