Higgo, the porosity is obviously not a bad thing necessarily, it just made it more difficult to tubeless them. I guess it depends on sealants as paul_m's experiences would suggest.
One reason I'm keen to ditch ghetto and move to full UST is the random performance of sealants, Stan's has repeatedly let me down, wheel milk solidified in weeks, Joe's couldn't seal microscopic pin holes, etc etc.
Re: the ADvantages, the sidewalls held up fine for me but I used them mostly on 'natural' rooty and loamy stuff so they rarely had to fend off big rocks.
I've already put two holes in the sidewalls of my UST ADvantages, hope it was just bad luck!