I’m amazed to hear so many people having issues with the fabric bottles – I am using the toolkeg on my Aeris 145 (and previously a bottle on an On One 456) and in weeks of use including BPW & Windhill it has only dropped off once (very heavy landing off a drop in Quantocks). Using the bottle whilst riding rough trails is a challenge for sure, but overall I am very impressed with the system.
I think the key is to get the right amount of torque on the bolts as you need the plastic collars to reform slightly.
Can’t see why anyone would ever have problems with using them on a road bike.
A couple of mates tried the magnetic ones and lost bottles frequently on cattle grids and cobbles.