The BT adapter in my 2011 MBP seems to be failing and has started not to work anymore after a few sleep/wake cycles, so I got myself a BTD400 so I could continue to use my Magic Trackpad.
First time I tried it when the internal adapter went on strike the BTD was detected and usable after just plugging it in. The 2nd time, tonight, took a bit more effort and a reboot as that failing internal adapter can apparently really make the system instable.
Anyway, is it normal that the BTD400’s led blinks slowly under normal operation with the trackpad connected? That’s frankly rather annoying!