I’ve mostly had indoor/outdoor cats, and all have lived to 16-20. Yes, it does depend on the cat. My beautiful brown tabby (who lived to 16) could NOT be contained. I had neighbors who swore they saw him look both ways before crossing the street. 
In certain areas of the US, it’s not advisable to let cats out, mostly due to coyotes and foxes.
We have had many cats over the course of 35 years and all of them have been house cats only, whether we lived in an apartment or in our house for 21 years. They have lived to be 19-20 and were all very well behaved cats. Only in the past 10 years have our cats have access to a terrasse or balcony, completely closed and because of their ages they couldn’t jump the fence 
. They went outside for an hour or two to soak in the sun if there wasn’t too much noise but they always preferred being indoor.
How do birds know to be wary of the bell sound?
I think the brightly coloured collar might work, though only if it is a breakaway cat collar.
Well said, I too have rescued many stray/feral cats and get everything you are saying! Love the birdbesafe collar!
We sit for an avid hunter and she has both a collar and an attachment which seem to foil hunting attempts. The bigger attachment is flexible and doesn’t impact her movements.
Apparently the collar works better than bells to deter birds. The Collar That Can Stop a Bird-Killing Cat - The Atlantic
Yes, @Wavingfish , the Birdsbesafe is not truly a “collar” but a collar cover, designed to slip over a breakaway collar to keep the cat safe.
Have to agree that cats are happier when they can be indoor-outdoor. Both environments appeal to all parts of their personalities.
Our older kitty was always an indoor-outdoor cat (but we never let her out after 7-8 p.m. – so she’d stay inside at night). When we downsized two years ago, now poor kitty is all indoors. She does not like it and is not happy anymore. So I am beginning to train her on a leash. It is slow going but hopefully she’ll get used to it and I can walk her daily to give her the outdoors she craves.
Will try to train our younger cat on the leash, too, once I get older kitty on board with it. 
Yes keep them inside, please. Speaking as a house sitter who had a cat escape from his harness and lost for more than 24 hours this is a terrifying experience. Do you have time to make some kind of catio, a screened in porch/verandah? Or even a window shelf. plenty of example on U tube.
The rescues where I live require potential cat adopters to sign a document stating that the cat will be indoor only, and won’t adopt to people who let their cats out.
