Finally completed spec ops last night on single player. Echo ops wasn't too difficult once i'd learned a few things by playing it solo;
1. plant (hidden) claymores after clearing each checkpoint on wetwork and armor piercing to cover the invariable hasty retreat and to catch pursuers off guard, in ambush
2. on the final stairs on wetwork, lure enemies from the top level down the stairs and shoot them from underneath/behind the stairs on the lower level. I found the left hand breach option the easiest at the end.
3. only use the .50 cal on armor piercing, the intervention's clip is useless when facing 3 juggernoobs at once; the best place to snipe them is when they come through the sliding fence/gate after the first breach; hs to knock them down then hs, hs again.
4. High explosive requires that you lob stungrenades to buy you time to escape when you are being surrounded and outflanked; not doing so is death
5. Lead (run away from, to give the tactic it's real name) the juggernoobs around the perimeter of the favela map, reloading at the origin spawn and the bottom right corner from there; this gives you enough time to get off 2/3 thumps from distance, and to hit them as they come round corners. Often you'll hit 2/3 enemies at once and get 2/3 kills at once. Oh and watch out for barrels.
I found this easier single player than co-op, as co-ordinating assault (especially on delta ops - wardriving) was really hard to manage when everything went mental. However, I absolutely loved the sniping ops co-op, counting down and sniping on mark through chernobyl was an absolute joy and I look forward to dlc. But now, it's time to pluck the multiplayer cherry...