A One Spot worked fine for me for a good while, but when I added a fuzz (not a Source Audio pedal) I started getting some 60 cycle hum. That was the fuzz I wanted to use, so I switched to an isolated power supply, and the noise was gone.
So my takeaway is that the One Spot is value-priced and works for some combinations of pedals--but not others. If it works for your personal assortment of pedals, great! It's an inexpensive experiment to try. But if you get noise, ya gotta pony up for an isolated supply.