Topeak here as well.
Also managed to break the clip (on the bag itself) after a crash, had to pay about a fiver for a new one.
Ordered a couple of spare saddle mounts to allow me to swap the pack between bikes, but the standard mount won't fit on a Brooks B17 narrow, so now have a spare.
Also have tried the Lidl one – no loop to fit a light and fiddly strap – wobbles about a bit as well, which I can't feel from the saddle but apparantly looks amusing from behind.
On my second Lidl one, managed to wear through the first with a Race Face Deus XC seat post in about a thousand miles.
If starting from scratch, would probably get a clipless Topeak wedgie pack or one from Edinburgh Bike Co-Op, which look fine and are very cheap.