i did the move from Atlas to an LCC. It is a little bit of a lateral move meaning I did not go to a Legacy or FDX/UPS , BUT contractually is a major improvement in several aspects.
1. not 17 days on a row on duty
2.i can still get a lot of days off in a row IF I CHOOSE SO
3. 1st year pay-rate cut, BUT many more credit hours per month and 2nd year pay it will be higher than if i had stayed at Atlas on 3rd year pay.... plus upgrade here is at 3yrs (or less)...so...
4. I did my homework and generally no ACMI has a better 401k than any LCC (over 12% defined contirbution)
5. no severe and constant changes in circadian rhythm
plus everybody is happy here.... i enjoyed the experience at atlas, but most of the pilots were miserable

so far so good... i hope this helps