To the best of my knowledge some will and do need feedback from there host device they are powering. This is why we trick them into thinking there in there intended environment, its not always perfect, but we try and get as close as possible to getting the best most stable voltage for loads possible. Some units won't play ball no matter how hard you try.
Its unkown territory, unless someone out there has trodden the path before (like the RC forum guys) the biggest user of these things. The single biggest fear for me, and others trying new units is what's been said many times before....Electrical noise on the output. If we get a quiet supply its a big bonus. I'm not going to pretend these things won't make noise, because they can, and badly in the worst units. But having said that its possible to find high quality units that put out no more than a few tens of millivolts noise, and this is well with in usable noise limits. RF gear is by its nature is fussy about its power source, but there are many units that can be used with no problems. A lot of the new psu's sold by radio retail traders are smps, but these are very good quality units, finding server or atx units with as good noise propertys is not easy. But not impossible, I don't have half the kit I could do with for noise testing, but do the best with what I've got. Some hours connection to lighting, halogen typically for testing stability, then connection to a none critical radio for some real time use normally determines if there exeptable for radio use. After a few overs with other stations you get some idea if the unit gets a green or red light. Ideally I would like to do testing under various loads whilst monitoring noise with a scope. But I can't take it that far at the moment sadly.
Maybe someone else can take up that challenge before me ! But back to your question, what where trying to do is not perfect far from it, but we try to get as close as possible, and it is trial and error stuff, only time and use of a unit says if its any good for radio use.
CB call. Shipwreck.