Boards are obviously originally made w/ crummy Al electrolytic caps for cost reasons. But when recapping the labor is going to be more than the entire initial board cost.

So, when recapping, why not use tantalum caps? Those aluminum electrolytics aren't even allowed in avionics. You generally won't be able to use equally high values but you won't need them either due to the lower ESR, better RF performance, and the vastly better lifetime values of the Ta caps.

The only problem I can see is that a couple of the caps may affect the control loops of low voltage regulators...