Another fan of the Trail Attacks here. My experience is two rears to one front, which only adds to their value. My second front was nearing 12k at which point I needed a new pair for a trip. I fitted a pair of old spec Tourances that I’d had in the loft a few years and needed to get used, and although they’re great, they‘re noisy and the fronts almost worn out at 6k. I’ve another pair of the TA3s waiting to go on for this season, plus a second rear for when needed.
Going from the OE Bridgestones to the TAs was quite a shock, huge difference, much lighter steering especially. By the time the TA3 front was removed at 12k it looked pretty aweful. Very 50p shaped, yet it rode just fine, and still gripped in all weathers.
Unfortunately I can’t say exactly how long they last, as I’ve needed to replace both rears before being worn out for trips that required a new tyre. Both did roughly 6k having a thousand or so left, in fact the second rear is in the loft as it still has enough that it could be put back on if needed.