We just got shipment of Uinions so I finally got to get my hands on some Atlas's. To me they seem to be the most promising Union to date. I have a bit of worry that the heel area may ultimately collapse under hard riding and or heavier riders over time (like 100 days maybe) but thats it other than the toe area. The straps are literally impossible to get to fit right. I spen 2 hours playing with all the settings you can on the binding with both the K2 Maysis and 32 Lashed. No matter what I did it will pop up on top of you toe if you wash out toeside or take any kind of digger. With a less than ideal fit, they'll just pop up under hard riding.
If you go Atlas see if you can wrangle some Burton caps. The ratchets seemed to fit on the Union ladders (but I have not ridden or know anyone that has to confirm long term pheasability) so you can just use the whole strap and ratchet. Which s good casue the Union toe ratchet is sub par.