I've tried the spin-fit, and for me, it doesn't sit really still with proper insertion particularly with the A3. Due to the weight of the drivers, the spin-fit(which is longer in length) made it harder to get a proper fit with the weightier A3. (no problem with other IEMs)
I was just wondering as I know they are a bit longer - I prefer my Spiral dot tips anyway.
I just went to the Sony shop (Japan) and tried the A3 with the MUC-M12SM1. I really Like the xba-300, they are cheaper, sound very nice and are small and sit really well, BUT I can't help but smile with satisfaction listening to the A3, damned usb drive,
Frankenstein bolt looking things