I don't think they do interfere. SPP are running 2 X Heden systems across town (not strictly Carats but the predecessor the HLC which still operates on Bluetooth). I believe they are also running Bolts on both cameras and as far as I know the only thing that they have had wireless issues with are the Redmotes.
The Heden units were paired at the start and are now getting towards 2500 hrs of operation in the last year, no problems reported so far.
I'm not entirely sure how long they have been running the Bolts for, but at least the current series and the previous.
I am assuming that the Carats are running the same wireless as the HLCs, but my understanding is that they are very little differences between them.
re: *a brief slightly off-topic note* (J Morgan)
I don't think the range is fantastic, I wouldn't expect that they would perform as well over distance as a Preston, which I have managed to get up to 1000m range with. In most circumstances you would never want to be any significant distance from the camera to pull focus and the more important aspect is that it is reliable within the normal range. In the case above, the 2 HLC units have never dropped out on set (2 X Hedens, 2 X Bolts, 2 X Redmote and the usual number of phones, etc running Wifi & Bluetooth). From what Heden says you can have up to 256 operating together without interference and the reconnect time after dropout is a matter of seconds. If the units stay connected within a 60m range I'd be fairly happy.