Hi,
I haven't noticed any real difference between the Avon and the M-Parts items and have used both over recent years. Both are slightly taller, about 5mm, than a real original made by Dunlop. Both seem to give a similar service life unlike the cheaper ones with no patent details moulded into them.
Moulten own the rights to the suspension cone and AVON and whoever M-parts are using are licensed to produce them.
Terry