Adas doesn't do enough armor damage for me unless it's amped through the roof with AR III amp/Incendiary IV and used on a Marksman class. I mean.. if you use a Disruptor Adas on a Juggy and draw Reapers.. you're not really going to be very effective.
I like the Adas on the Juggy. Incendiary rounds and siege pulse specced for armour damage is still pretty good against reapers. most games I take a collector SMG secondary on him, in case armour gives me a problem but I don't have to use it.
I tried the krysae on him yesterday and it's pretty good. Drew Geth which helped, and rio, which really didn't, but it still worked for me even though I was last to the spawns.