I guess the chances of it being usable, or at least repairable are higher than if it was an A2000 or A500 with an old RAM/RTC expansion with exploded batteries. But you do have to remember a lot of old A1200s, A600s and CD32s develop capacitor problems which can stop things from working until they're replaced, but at least the damage caused by them exploding is less than that from a big old barrel battery.
