Ugh, I have a friend who just went through that dilema.

The organization she works for is trying to bust her union, and so they hired some management consultant types who specialize in union busting, and those consultants found a loopy way to use the contract where they could force some downsizing in exactly the departments full of oldtimers with enough seniority to bump junior members in other departments, and it had the effect of making the bumped young workers think that unions are horrible things, combined with people in the new departments not really liking the oldtimer coming in because they know she's there only because she used seniority to bump for the position, combined with how the oldtimers were unhappy because each department works so different, they were basically having to learn a whole new job that takes experience from scratch. You can probably already see the union busters giggling and rubbing their hands with glee.

In her case she had to take the option, because she's got dependants, but she said that if she didn't have the dependants, she would have looked for a job somewhere else, because she thinks she's still young enough to pick up a new skill.

So... translating from her experience to your situation:

1) Do you have dependants? If so, how dependant are they? The fact that you've got seniority means your dependants might be older and more adaptable to changes in the family income structure, whereas the other guy being bumped might have a young family, but you could also be burdened with the kind of dependants at an age where they're looking for help in college, which is no financial picnic. If it looks like your obligations to dependants are more than the other person's obligations to dependants (quite possible given how people are starting living at home longer and starting families later in life than they used to) then you have to accept that obligations to dependants implies a commitment that's virtually out of your hands.

2) Is it an industry that's easy to retrain for? Is it an industry that's easier for *younger* workers to retrain for? Be realistic. If he's younger, then given the nature of your industry and whatever it is you do, is it going to be easier for one or the other of you to retrain? If it's going to be easier for him to retrain than you, then that's another decision that's basically being made for you.

I really do understand what a dilema it is. The option of job bumping has become the union buster's favorite ploy for shaking up credibility of unions among young people, and it's disheartening to those with seniority, and I know that the smart union leaders are starting to rub their chins and think about how it's possible they hadn't thought it all the way through in terms of how that one could backfire, and so have those leaders figure out a way to fix that glich in the next round of contract negotiations, but in the mean time you do have at least two basic questions to ask that answering will make the decision for you: 1) Between you and the other guy, which one is more burdened with obligations to dependants, and 2) Between the two of you, which one is in a better position to retrain. Identify metrics for each of those, and the answer falls out of the hat.