I have used the older design Metzeler Tourance on several GS Adventure bikes since 2004. (R1150GSA, F800GSA, F850GSA). I find them durable. less expensive than the Next or others. I get about 12K miles on the rear and 14K on the front.... no off road riding, only some dirt roads... but mostly highway. The shortest distance I ever got on my rear tire was 5 miles... installed new and picked up a spike through the side wall coming home from the repair shop. What a waste!
In the US, I belong to the BMW MOA organization and have their towing and tire replacement service. I already took advantage of a damaged front 21 inch tire replacement due to nail (about 9K on tire but greater than 2/32 tread insurance company limit) The BMWMOA.org offers membership for about $50 and tow/tire damage replacement for $59 per year.