I think its all down to your preference and what you use your pedals for. If just for home use daisy-chaining out of an NS-2, TU-2/3 or a LS-2 etc will make barely noise (I daisy chain into 4 Boss and 1 EHX pedal out of my NS-2, no noise at low volumes with it off). At higher volumes you might hear a bit of sound but meh thats what the NS-2 is for.
The VLPPP2 is fantastic but for $200... I wouldnt buy one unless I was playing live. And no I dont think the boss is isolated... Could be wrong.
Well using your LS-2 there will be ground loops. Using a VLPPP2 you will eliminate the ground loops. So as radioheading said its a personal and financial choice. Some pedals are more sensitive to ground loops than others.
I'm not sure if this is relevant but are ground loops/noise issues more a U.S. problem than a european one...? i use a normal boss adapter to power all my boss and other pedals except for the tube overdrive which has it's own,don't use a power conditioner in my rack and have run two amps off a CH-1 in stereo with no hum,phasing or noise issues and lately i am running the stereo wet rig with my amp also with no major noise,hum or any other issues to report....is it someting to do with the fact you guys use 110v power in the states....?...