I spend a lot of time reading forum posts and I can assure you that I have not come across a single brand that has a leak proof inflatable mat (with or without insulation) .
Some time it is user error, that is leaving the mat in the sun fully inflated (it will delaminate or result in a permanent bump, I have done that) or cats have had a go at them (done that too) or set up on dirt over spiky stuff , however often enough they just leak.
And yes I do have one with a mysterious slow leak that can't be found ...
Come to think of it my bike tyres are not all that different.
Franco