Not on a ST.....but ST1300EVE has one on the rear of his GTR1000 and speaks highly of it for 2 up with the trailer.....
Yes on the GTR1000 2 up and trailer 30,000 plus k.....but being a conventional tyre not radial you do feel the extra weight going around and probably not as grippy however i don't ever really test this feature in any tyre. Just finished 8,000k on my ST1300 2 up and trailer with Pilot 3 on the rear, not impressed but i may have done some damage before i got to an ideal tyre pressure? the soft edge compound scolloped fairly severely. 12,000k throw away i think, The Pilot 2 on the front went really well and will probably go to about 16,000 so happy with that... might try a pilot 2 on the back.