Couple of things I noticed on my first couple of LFG tool uses.
I had defaults selected and went to first group.
1) One person didn't show right away (bio break) and another group member started the vote to kick. I did not vote (was trying to ask group member why he started this when it had only been a few minutes) but member was kicked anyway. A non-vote shouldn't be counted as a yes! I would assume a group vote should be unanimous in order to kick.
2) We ran into the "group is valid" issue after member was kicked and had to drop the group and rejoin queue. This is well documented by now I assume.
3) When queuing again, now my defaults were set to have HM FP tier 2 (Lost Island) selected even though it was deselected the first time around. As far as I could figure, my defaults were now changed to match that of other members of my first group. That shouldn't happen. I didn't have HM Lost Island selected because I am not appropriately geared for it and my defaults shouldn't change based on what other members of my group have selected.
Just throwing those out though I am sure others have already put more indepth info out there on these issues.