I have had my 910xt slightly mal-aligned in the quick release holder…the 910unit felt like it was on right, looked as if it were on right(at glance), and even went through an entire swim in the pool without falling off BUT as I was putting on my shirt after the swim…the 910unit was knocked off of the quick release. I put the 910unit back on and THEN noticed that I had put the unit in just ever so slightly wrong. As you are putting the 910unit into the qr…it is very easy to THINK you have both locking lips engaged as you twist the unit in…but you may only have 1 side locked. With only 1 side locked…everything seems normal, you feel a click s you are supposed to, the unit stays put during normal activity, and at a glance it looks as if it is sitting in the qr.
Bottom line…press evenly and firmly down…then twist and make sure your 910 unit is sitting completely flat against the qr. If only one lip is engaged…the 910 unit will sit at a very slight angle on the qr.
When properly enganged into the qr…i cant imagine this thing coming off…even in the middle of a race swim. I have tested it out for my own sanity and cant get this thing to come off when placed properly. hope this helps some.