I have been using them for several years now. I love them. I highly recommend you look for a used set of drivers and give it a try. Radio Shack made some decent drivers that were good for a first pair and give you an idea of the sound.
In general an open baffle or open back speaker will be challenged for LF response as the back waveform at long wavelength frequencies can cancel with the front waveform. There are some exceptions where this is acceptable or desirable like guitar amps.
I am not familiar with these products but recall the old electrostatics were dipole radiators.
And big drivers are not good for high frequencies, including small opening angle.
Open drivers also emit sound from the back, that bounces of the back wall and colours the sound.
IMHO, 1950s audiophool stuff.
Yes they definitely have bass issues but the midrange is wonderful. I highly recommend you get a cheap pair of drivers and try them to see if you like the sound. I built my first baffle out of diaper boxes and they intrigued me enough to build a proper baffle. Now I listen to them almost every day.
Thanks for the responses, guys. I had a gut feeling that an open baffle design didn't really have a place in the studio due to phase issues, but you know.. What if they were a great option and I was just using old dogmatic ideas? I'd be a fool. Thanks for the confirmation.
They are an interesting option to check a mix on, and can be fun to listen to. I have several 800 ohm small speakers that will run off a headphone amp, sounding really good in their way. Making a full range array out of multiples, on a baffle board, improves the sound. Antique style tube guys will run speakers like that directly off a power tube, cap coupled rather than transformer coupled. Lots of different methods for enjoyment listening, but won't ever be first choice for serious monitoring.