well mathematically if you have 400 pilots and keep the same a/c order then it appears the upgrade time lengthened by at least 200...
i am sorry to hear they shoved you out of their playpen. good luck on the recall effort.
Yes, upgrade times will lengthen for some people, depending on the way the list is integrated.
With a slotted seniority integration, you can go to a straight slot or a percentage slot, then fence them for 3, 4, or 5 years to protect upgrades.
In a straight slot, the #1 MEH F/O would be slotted right behind the #1 AAI F/O, the #2 MEH F/O would be slotted right behind the #2 AAI F/O, and so on and so forth until they got all 200 guys accounted for. This would put 200 MEH pilots at the top 200 of the seniority list and would depress the upgrade expectations of the bottom 600-700 AAI F/O's once the fences ran out - a pretty crappy way to do it unless you're a MEH F/O, then you just got super-senior overnight.
In a percentage slot, the #1 MEH F/O would be slotted right behind the #1 AAI F/O, then the #2 MEH F/O who is #2 of 200 at MEH goes in behind the same percentage seniority-wise as the #2 of 900 AAI F/O, the #7 AAI F/O slot, making the #2 MEH guy #8 on the combined seniority list, and so on until the most junior MEH F/O is under the most junior AAI F/O. This is, by far, the most fair scenario, as it doesn't give a MEH new-hire super-senior bidding status at the top 20% of the combined F/O list overnight, but puts them just as senior or junior with a combined airline as they were pre-merger with equivalent bidding rights for monthly lines, vacation, and base changes.
Either way, fences for 4-5 years or whatever they work out keeps MEH guys upgrading only for their own ranks' attrition (the growth they expected pre-merger) and the AAI guys upgrade with new deliveries (the growth they expected pre-merger) until the fences come down.
In my perfect world, fences stay up long enough to take deliveries of all the aircraft AAI currently has on order. Any orders that are announced AFTER the seniority list is combined become fair game for all pilots to bid once they are delivered on-property.
In this scenario, they'd be using the existing seniority list as it existed on the date the acquisition agreement was signed which means, the longer it takes to get this done, the more pilots here can upgrade, the more that are on the seniority list, and the better off the senior F/O's will be.
Hope that made sense.