I've used both the old style bag-loop and the SQR bags - be warned that if you have a lot of set-back on you saddle (for me due to long legs/thighs or it might be a steeper seat-tube than is ideal on your frame), then you will be hitting the bag with your thighs on every pedal stroke. It annoys the living piss out of you and you then sell the bag after one ride with it.
I've used both the old style bag-loop and the SQR bags - be warned that if you have a lot of set-back on you saddle (for me due to long legs/thighs or it might be a steeper seat-tube than is ideal on your frame), then you will be hitting the bag with your thighs on every pedal stroke. It annoys the living piss out of you and you then sell the bag after one ride with it.