I believe that seniority is SACRED.
If the airline you work for has it; don't touch it, leave it alone.
I have a friend who has been a 737 F/O for atleast the last 5 years; and has been bypassed for upgrade to captain by his juniors and new hires countless times.
In my opinion,not having seniority sows low morale and does nothing for camaraderie among pilots.
I consider myself lucky because the airline i work for honors the seniority system.