I think everyone would accept that Frankel is one of the best milers of all time, if not the best. There is only Brigadier Gerrard and Dubai Millennium, that I could put forward as possible alternatives. For me personally any doubt was removed by his scintillating performance at Ascot this year. I agree that, other than the clock, he can only beat what's put in front of him and unless something can give him a race, we will never know just how good he is, particularly beyond a mile. The fact that HC wanted to avoid the stiff Sandown track for Frankel's first attempt at 10f is understandable but also confirms that he could be vulnerable. At the end of the day, Henry does what's best for the horse and I respect that more than anything.
Any talk of Frankel being the best racehorse ever is pretty meaningless to me. Who is to say the best miler of all time is any better than the best sprinter of all time, or the best middle distance performer of all time, or the best stayer of all time. If they ran against each other then no doubt the outcome would be determined by the distance and conditions of the race. They should all just be respected as being Great in their own right and we can feel privileged to have witnessed any horse who fills any/all of those categories, or indeed is anywhere close to it.
I'm sure everyone would love to see a scintillating performance from Frankel over 10f but the opposition may not be up to the task of bringing this about. I personally would have loved to have seen Frankel v So You Think, whether it be over 8 or 10f, because I believe he is the best yardstick we have; a horse who consistently clocks fast times, win or lose. And especially as AOB has eventually listened to the previous trainer (by his own admission) meaning we may even see So You Think to better effect.