So, after starting a discussion about swapping out a talent for a newer one (as most pilots would someday be able to perform a Barrel Roll, not just a cloned pilot), how about this?
Transferring a complete specialization from one career to another. Granted, this might not be applicable or logical in any and all cases. But even FFG did this themselves. Proof? Smuggler / Pilot and Ace / Pilot. The talent tree itself is completely identical. It's just the differences between the career skills specifically for the Smuggler and the Ace careers themselves. More proof? Spy / Slicer and Technician / Slicer. Again, the Career - career skills differ, but not those of the specialization. So what if a player asks you to build a Fringer / Pilot? Or a Bounty Hunter / Marauder?
Mind you again, these examples are not too far fetched in my opinion. Feel free to differ, of course. But it's not like asking to be a Diplomat / Ataru Striker, for example.
Or should such players always use the extra XP to buy-in into other careers if they want a specialization outside of their starting career? Even if FFG themselves provided a few examples of how a specialization can be part of multiple careers.