Thank you for the replies.
I don't own any 2.4GHz wireless
microphone equipment (including the
Sennheiser D1) and I don't plan on owning any, nor would I recommend it to anyone else.
That said, I've found myself in the fortunate position of working in a relatively new
venue that happened to
purchase a dozen
Sennheiser D1 units operating in the 2.4GHz band.
Sennheiser did a good job on this equipment from most perspectives, they are well constructed and easy to use.
Unfortunately, I wasn't present to witness the prior problems but since starting work in the
venue I've encountered a few issues myself - a dropout or two, excessive battery
power drain on the transmitters compared to similar
UHF packs, and instance of the audio from one transmitter transitioning to a low-res, garbled, phase-y type sound (the audio is digitally encoded before transmission, and to me that sounds like a case where there wasn't enough bandwidth to transmit a full resolution signal).