I'm sorry, but BMI is an A320 operation with a tiny A330 section. It's also a financial disaster. If ex-BMI pilots get to maintain their current pay structure, keep their commands and have 'dead man's shoes' access to commands previously held by BMI pilots, then your T&Cs haven't worsened. The loss of the minimal amount of A330 flying can be offset by the fact that your new company has a future. Hopefully you will also have a decent bidding system, roster stability and a huge staff travel network.
I've heard BMI pilots argue 'our slots will be used for longhaul so we should get to fly longhaul'.
The slots do not belong to BMI pilots. BA are buying those slots, BMI is just part of the deal. The slots are being bought with profits which BA pilots (through increased productivity and paycuts) helped make. If you want to allocate ownership of the slots to a pilot group, then they will belong to BA pilots.
The notion that an engagement freeze negates the negative affect of a DOJ merger on BA pilots is also unfounded. From the point the freeze ends, you would have access to fleets/seats/lines of work ahead of pilots who have already served many years in BA. I don't think you'll find many non-BMI pilots who feel this would be reasonable.
If ex-BMI pilots want to enjoy the vast longhaul network the BA has to offer, they'll have to join the back of the queue like everyone else.
I appreciate that this is very blunt and I'm sure some will 'find the tone unsavoury' but there's no point in sugar coating it. I wish all BMI pilots the very best, but to expect your service in a borderline-bankrupt shorthaul airline to allow you leapfrog pilots in the company that is buying you is entirely unreasonable.