Doing a 3 man t3 rift runs yielded very little Legs. We did however get two smolderings out of 4 rift guardians. All in all we ended up with 2 legs (no set items) & 2 smolderings a piece in about 3 hours of gameplay. Doing casual CoA chest runs would yield 4 to 5 legs an hour (and by casual I mean watching Top Gear, and doing the runs at the commercial breaks). Granted we leveled 3 paragons doing the rift runs, got a ton of rares which we gave to one guy because he was in need of mats, but I am still having a hard time comprehending how doing pure chest runs can yield so much more legs than doing rifts which IMO have as many chests available to pop as CoA did. Meanwhile two other folks were doing Manglemaw and were hitting about 5ish legs per hour. Again I submit to you that we were killing rare packs, uniques, and purps in greater frequency than their MangleMaw runs and yet they were getting a greater drop rate than we did.
I have a running theory that adventure mode has a lower leg drop rate overall than storyline mode. It could be just bad RNG, but it always seems better to run mindless bullshit over and over again than actually play the game the designers want you to. My thought is they need to either guarantee a legendary on rift guardians, or at the very least guarantee a smoldering. I honestly did not notice a difference in the leg drop rate last night compared to any other night. Instead of nerfing redundant, mind numbing game play, they need to make the carrot bigger for adventure mode.