Well, tantalums aren't subject to drying out like electrolytics are - which is their failure point - as we know. From what info I've gathered, they can fail from moisture intrusion or by being accidentally shorted. Then their life expectancy drops off rapidly. However, the last radio recently repaired was a Uniden PC 244, it had a failed tantalum at the audio chip. When I've rebuilt some old 148's, a couple of them had tantalums that were far out of spec, so they were replaced. Not sure of their life expectancy overall. Make it an option with your kits and then see how it goes from there? The BAT85's in the last kit you sent was a real useful item! Their forward/turn-on voltage is lower than the STMicros. Good stuff!