I hate to say it, but that sounds like a lateral move. Sure, you might make more in 5 years so JB could be a good option. (Consider also what would happen if hiring slowed and you ended up in the right seat of the 320 or left seat on the 190 for several years at current rates.)

However, there are probably several better options out thare right now that would be my first choice. These 'other' options either provide better seniority or better pay/benefits. Don't forget to factor the high cost of living in, or commuting to, current and planned JB crew bases.

This is not a slam on JB, just a realistic consideration now that the quick 320 upgrades are a thing of the past. And if the 'other' options don't pan out JB is still a fine 'plan B.' JB is probably a better job than many 'regional' jobs yet is nothing special once it is viewed without blue-tinted glasses. My $0.02.