If I was management and I had a staffing problem, I would prefer an LOA that only raised new hire compensation. For a pilot group to agree to those changes, especially in contract negotiations, would give away good leverage to get a good contract for all.

When Endeavor (Pinnacle and Mesaba) pilots had staffing problems, they secured $23,000/year annual increases for every pilot on the list. So instead of an extra $23,000 for new hires only, every pilot on their list saw a direct increase of $92,000 over 4 years. From a pilot's perspective, that is the best way to negotiate first year compensation issues.