In reply to Babika:
> I did exactly that with my tent and put along zip down the length of the bag as I was utterly fed up with trying to roll super tight and squeeze it in
I have a friend who's just acquired an ancient Macpac backpacking tent and the only thing wrong with that is that the bag has delaminated. (Seems to be made of more or less the same stuff as the flysheet, which is absolutely fine.)
I have an old sleeping mat bag (that's outlived the mat), and I'm wondering about giving it a sort of 'corset' so that the tent will slide in easily quite loosely rolled up, but then the bag can be cinched up on the lacing to compress it if necessary to save space in the pack.