Your brave
Scouting? Those guys are the SAS ffs. They do a little reckon and then nuke the place. If your Toss and see those badboys coming before you have a number of stalkers and sentries its GG. Still haven't figured out a Toss counter to them.
Its the speed and maneuverability of them that causes the issue rather than the toughness.
A Stalker can kill them in like 2 shots or something. But, If the reapers attack the mineral line, and you move in to engage, they leg it, hop over an edge, run round your base pop in on another side, blow up a pylon, wait for your stalkers to give chase, hop over an edge, run around, back into the base, hit the mineral line again... Rinse repeat until GG. Hateful sons of *******
My only counter to them was to switch from Toss to Zerg.