Speakers hung from ceiling on aircraft cable.

Opinion question:

We are thinking of suspending a pair of KEF LS50 speakers from the ceiling using aircraft cable. Do you think having them not rigidly mounted will diminish bass? Will the woofers cause the speakers to move?

This is a practice used in baffleless dipoles for bass and midrange drivers,  where the drivers hang on a swing, however generally not suspended from the ceiling but a frame.

Doing without the baffle avoids vibrations transmitted to the panels. Of course this requires significant eq because of the 6 dB/octave slope before the dipole peak, which is where the drivers should be operated. I'm experimenting with this now.

Anyway, probably not doing much hanging boxed speakers in a swing.
If you have the right speakers yes. Mine are hanging fine. 15 year's now. There also inverted with springs, between the cables. Then you build soffits around the monitors.  There is a very good reason why very hi end recording studios (mount) there monitors in this fashion.  One is bass, two imaging, three is woofer bounce, from the floor. That is my experience.  :-)
I had a Mini Utopia speaker suspended from 4 piano wires behind a perforated drop screen in a multi purpose home theater for 5 years.
Worked fine crossed over at 50 HZ.
OK, I can't resist this....*s*

We've been to concerts where the speaker arrays weigh a lot more than a LS50, typically hauled up with chain hoists.  Obviously, whatever you hang X from needs to be able to cope with the weight.

I've had three bookshelf speakers, vertically aligned, per side hanging in my shop.  Each side weighs 'bout 60ish lbs., affixed together with 4 threaded rods with some blocking to basically 'clamp' them together. 
Nil vibration between them...and no holes either.

Suspension is chain, overrated for the weight involved; this is done in a fashion to allow the 'array' to be tilted forward about 10 degrees.
This is easily adjustable...if it's on the floor.  Not a fan of manipulating heavy objects in mid-air....

BTW, the speakers are motionless even with heavy bass lines...cones moving to and fro cancel out, but it's not a concert hall either.

If you're going to weight a speaker for stability, do it on the bottom. Top-heavy anything hung is not a good idea....

In a 'residential app', the occasional 'bump' needs to be considered. Do not stand up underneath them, nor walk into them.  High ceilings are preferable.

You do give up the floor effects on bass, but it works at the ceiling too.
And there's always the corners...

Have at it, J
....too much work to test the idea......I would think it best to leave it alone.