I've been using the One Spot since day one for my Timefactor with zero problems or noise. However, if ANY other pedals are connected to the same power supply there will be some hum/interference. So, only power a single Timefactor per One Spot (i.e. all other pedals should be powered separately).
My unit shipped with a U.S. power supply and as I am based in Europe, I had to find an alternative and have no problems at all so far.
Hope this helps!