" The one spot doesn't so this would mean that it would not put so much strain on the pedal. "you can never have too much power"
the strain wont be from the pedal. If theres any strain, it will be on the adapter.
one spot doesnt has limit on how much each outlet of the dc chain can provide. As long as all the pedals connected through the same dc chain, their total current drawn doesnt exceed beyond the 1700mA rating, the adapter shud be safe.
With those isolated power supply, bascially each outlet is like having its own 9v supply for the pedals(thus the term isolated output). In these kinda power supply, usually there will be mutiple transformers that do the stepping down from main supply to provide individual 9v for our pedals. For current rating(how much juice it can give to the pedals) that will depend on the transformer used. Heres a diy isolated pedal power supply, some pics and info in there are quite useful
http://www.geofex.com/Article_Folders/Spyder/spyder.htm
For adaptor like one spot or dc brick etc, theres only 1 9v supply(230vac from main, thru adapter, step down to 9vdc) and the only thing thats distributed is how much current it has, to be drawn by different pedals for powering up
"Like if you isolate to 100ma each, what if the particular pedal needs more or just nice 100ma?
each pedal will only draw whats needed, to be powered up, no more no less. If the supply cant provide enough, either pedal dont work or worst case, the adapter be gone. Most gain pedals wont need much to power up(double digit mA or so usually). For modulation pedals, it can go up to several hundred