The ISO-1 is very light, so it does not add a lot of weight to a pedalboard.
Beware that It says 500mA on all of the 8 outputs, you can not draw a total of 4A with the supplied adapter, max. is 18W which equals 2A @ 9V.
I tried the powersupply on my main board, there is no noise and hum at all from it, so it works absolutely as Thomann claims.
Also note that here is no ringtraffo in the silver box, so there is zero magnetic interference comming from it, which probably also make it so cost effective since production does not need to use a lot on shielding the unit.
I use the powerplant for a small board that only has 9V pedals on it, although there is a doubler for 18V included 12V is not an option.