I use the AP-105 all the time in ceilings under 10' tall. 10 foot ceilings or less are pretty common... I would be more concerned when the ceiling height is more like 8 feet or under.
Worst case, all that happens when the <8 foot ceilings are in play is that you end up needing more AP-105's (or any APs that are integrated downtilt) than when higher ceilings(the norm) are found. In practice, that may mean placing ~20% more APs onto a given floorplan then when more 'normal' ceiling heights are in play. Just something to keep in mind.
The AP-105 has been our workhorse AP for the widest variety of environments you can imagine. Just in the last week I have seen it deployed in 8 foot ceiling, 10 foot ceiling, a 60 foot gym ceiling, and a 50+ foot auditorium ceiling. In all cases it works....