I haven't owned many, but my experience is that the auto-winding can be a weak point, sometimes needing replacement parts. Parts are available, but not always cheap, and not always in great shape. It can take some hunting, and even donor movements may not have usable parts. People often just wore these watches for decades until they stopped. If you can find one that has a credible service history, even if the service wasn't terribly recent, that would be good. That way at least you know someone went through and checked the condition of the parts in modern memory.
I would suggest that the maintenance history and condition of the specific movement is going to be a lot more important than the particular caliber. If you buy a watch that's not in good shape, it can be an expensive and time-consuming project, and given that the non-precious metal bubble-backs aren't holding their value very well these days, it could be a questionable choice from a financial perspective. So just because bubble-backs seem cheap at the moment, cost of ownership could be higher than a 60s or 70s oyster perpetual, which would also be a little more wearable in size. But if you love the bubble-back, you should obviously go for it. Personally, I'm not planning to buy any more, unless I find something really special.
