I would try to get the pattern you want before you sign.
4 on 2 off does not get you a free ticket for every rotation. You are limited to the same tickets as 6/2.
5/3 4/4 not available. Those who are on it will not get it back if they change.
6/3 is the best option for time off. No free travel days so if you are travelling to europe you lose 2 days travelling every rotation. You will also get hammered with no days off for your 4 weeks on. Just the 36 hours in 7 days rule.
Its not as rosy as it looks. Many guys leave as they didn't research it first.