First I ride an 1150GS so comparison is not so relevent and apologies for the saga.
I rocked up at Knockhill race track yesterday for a track day on my GS equipped with a pair of original spec Tourances and my first time on track since removing the ABS. The tyres had just 165 miles on them all damp to wet with sub 10C temperatures. There were still 1" chicken strips each side of the front tyre.
I had signed up for the intermediate group as previous track days had been frustrating in the slow group as people couldn't ride around corners. I was a bit nervous to discover that many in the group today were on dedicated track bikes and were starting the day on race wets and using tyre warmers.
First session misty, wet track, felt like about 8C, and I was happy behind the pace car for the two laps and then as it peeled into the pits we hit the straight. Hard on the brakes for the right hander at the end of the straight and just as I'm a bout to tip in the back wheel looses traction and I decide to go off roading through the gravel trap. Wet cold grip not great. Stability in deep gravel excellent
Later in the day the sun comes out, the track dries and things are much better. The fast bikes come howling past me on the straights (now fitted with sticky road or track dry tyres) but then somehow the tractor with the fat old rider is as fast as some of them through the corners. Things start hitting the ground hard on corners. In the right hand hairpin my foot gets dragged right off the peg but ¼ton of GS isn't easily deflected and we survive. Lesson? Hang off the side more, lots more. I start to worry about actually falling off the side of the bike but still the Tourances are gripping. On the power (what there is of it in an 86,000mile 1150) too early at the hairpin and the back end steps out far enough that I am yanking the bars hard left to keep it going the right direction, terrified I'm about to experience my first high side, but again we survive.
So, I know from experience that these tyres can do 10,000 careful miles front and rear. In the wet go a bit canny and when they wear/square they feel vague tipping in but if you have the confidence to tip past the tight radius they'll be fine. I got mine for £185 the pair fitted. Result. They are now nicely scrubbed to the sidewall front and rear and the rear blocks have some very satisfying marks were they started to melt and bits pulled out of them.
In the dry on a decent surface unless you hit the heads on the road you'll be fine. I should also say that I had the rear preload at maximum to raise the back end for more clearance.