I prefer Scorpion Shield for a few reasons
-it only takes one power pick
-it is defense based, but looks better than Ice Armor
-it looks good with Stealth Powers, Stealth Powers adding good survivibility to Blasters
I prefer Defense since Blasters' have a weakness with Status Protection, thus you can avoid some status effects easier.
You can build up Defense on something like Temp Invulnerbility or Electric Armor sure, but you are then going to have to slot for a LOT of defense. And as a Blaster the main job is Blasting stuff, which I am loathe to weaken in order to build for a lot of defense. At some point your build is giving up enough you'd have been better off going Scraper or Sentinel.
So my usual go to is .. Scorpion Shield, Combat Jumping, Tough, Weave, Stealth then build for 45% S/L defense with IO sets. If I have room I add in some Ranged Defense Set Bonus.