However, my own brief listening tests to a Cloudlifter suggest that it is very quiet indeed and the negligible noise it produces is more than compensated for by the benefits of additional front-end gain when used with budget preamps.
If there is a downside, though, I fear it is that there is virtually no bandwidth limiting at all in the Cloudlifter circuitry -- and the gain stage is DC-coupled. This means that subsonic rubbish from the mic is presented at a very high level to the following preamp -- which might well cause overload problems -- and there might well be a much greater susceptibility to RF interference. The former is likely to be an issue in any situation whewre the mic is being handheld, or in a position where there are significant air currents, or where substantial vibration is passed along the mic stand. And the latter could be an issue where there are radio mics, digital cables and mobile phones in near proximity.
I should emphasise that I don't have first hand confirmation of these potential concerns; they are conclusions I have arrived at from reading the product decsriptions, listening to the units and from feedback received from genuine users.
None of these potential issues are insurmountable, of course, and some may not prove to be practical concerns at all...
Technical Editor, Sound On Sound