For the past 10 years, up until Grizzly 3 years ago, we had cats that were indoor/outdoor. All of them had litter boxes, but they were free to go outside when they wanted. Of course, we made sure they understood that our home was their home before we let them out, and they always returned home. With Yoshi, the very first cat, we made the mistake of not neutering him in time, so he "ran away" as I used to believe (being a child). Sasha was from the shelter and he stuck with us for about a year. Then we had brought Grizzly home, a result of my friend/neighbour's cat "getting it on" with one of the neighbourhood's outdoor cats. Sasha tried to stick with Grizzly, but Grizzly was too playful and wouldn't stop jumping on Sasha's tail. So Sasha started staying outside longer and longer, and eventually found a new home with a house down the street. He would still come home every week, to see us and to have some food (but he would always turn tail and run away when Grizzly came into view). Eventually, Sasha started switching homes, not staying with one for more than a month. He soon made a home a few blocks away, and the last time I ever saw him was a couple of years ago, when he was sunning himself on the sidewalk in front of one of my friend's house (a couple of blocks away).
Now, we had Grizzly for 8 years, and he loved being outdoors. Unfortunately, he ended up getting caught in a cat trap that sprang up somewhere nearby, and we never saw him again (we checked the shelter and Animal Control, and he just simply disappeared). Then we got Willow and she was strictly and indoor cat. Buffy came 2 years later and she's an indoor cat too. The other cats were allowed outside because my parents didn't know any better, and all our neighbours on our street had cats who went outside. Unfortunately, since that cat trap appeared, there haven't been as many cats coming to our house.
I would advise you keep your cat indoors. If you would like them to go outside, they should only do so under supervision, and with a leash on (I let Buffy and Willow play in the front yard once a month, and they have to be on leashes because they've learned how to run away from us and hide under low cars when we want to bring them inside). Plus, it's kind of better, since if they get to go outside fewer times, they get even happier when they go outside. Grizzly would jog out and maybe jog over to the neighbour's house, but Buffy and Willow just start rolling on the sidewalk by our steps and then they go crazy in rolling in the grass and on dirt.