Before buying the Toyo T1-S I did searches on a bunch of forums, including the BMW forum to see how people liked them. I really didn't hear many bad responses. Also, when I went road racing, one of the instructor's complimented the tires and even rode with me to see how they felt compared to his Toyo T1 (not Toyo T1S) tires.
I've had the Toyo T1S on for about 8k miles of street driving, 5 passes on the drag strip and 2 road races and I still have at least 50% of the thread left. I felt they performed very well in all situations. I can't relate to your feeling of less grip after hard driving, especially since the grip felt constant during road racing.
Please don't see this as a flame. It seems like you have more experience with different tires, so your $.02 might be worth more than mine.
Ash
'93 SUPRA TT BPU