subwoofer suspended from ceiling?

I have an open trussed ceiling. I am thinking about suspending the subwoofer between two trusses. My question is as follows- will the quality of sound be negatively impacted if I move the subwoofer from the floor (concrete slab) to a suspended location up in the ceiling? Thanks for your help.
Not a good idea from a structural vibration point either.
I think within time you would be listeing to your roof, rafters and walls rather than the sub.
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We've done a number of designs with soffit mounted subs. There are issues, vibration, making a very rigid mount, but if you can over come those it can work well. In most cases the floor is simplier, and it's what most people do, but it doesn't necessarily mean it's best.

The 1/2 between floor and ceiling as Eric points out can sound very good. It cancels out the height mode which is typically the dominant axial mode. We do this regularly in our designs
Committed is what you should be for doing.Save that suspension for monitors or turntable on rigid pole.But Put this up so I can easily follow what happens.I am thinking of that scene in Young Frankenstein when they have to crank the table up to get the lightning.