I'm currently out on a trip with a captain who made a lateral move after 7 years (5 of being a captain) at another regional because he anticipatied things going way downhill fast for him there. He was right and it ended up being a good move for him. He wouldn't have fared well at his first regional. I'm sure there are hundreds of other people who have taken that gamble and lost it though too. The airlines are unpredictable and the regionals are even more unpredictable. If you do make a lateral move it will be a gamble. It could work out great or you could regret it in 10 years.