Not everyone wants to become a hot-shot surgeon in some super-competitive specialty. Hence not everyone will be working crazy hours like that 
The fact that I know people my age with one or both parents as doctors (surgeons, GPs, specialists, etc.) shows that it can definitely be done if you want to have a successful family.
I found through reading threads on PD, is that a lot of the "loud" posters who speak up about their concerns also seem to be very ambitious. So that's understandable.
I heartily agree. But you do realise, the specialisations that we're talking about are Emergency Physician, GP or Psychiatry right? Virtually all the other specialisations are as demanding as I've portrayed according to PD.
I've spoken to four GPs, three in person, one online, all of them were along the reply I got from the one I spoke to online:
"When you rule out medicine, surgery, GP, path, psyche, O&G, radiology and crit care (ICU, gas and ED), there's not a lot of other specialties left. Of course there are things like public health, rehab, eyes, skin and the like - but they constitute a minority. Suggest you have a look around the forum and outside sites to get an idea of job pathways available. Path, GP and psyche are currently the most common "easy" training pathways WRT lifestyle choices.
Would I have gone into medicine had I know what I know now? I knew about the pitfalls of the career in theory, but it has made a difference actually living through it. I most likely would not have gone into med with the benefit of hindsight - thought my problem was that other things didn't interest me or offer as much job stability as medicine did at the time I decided to do it. The main stumbling block regarding leaving the profession at my stage now is that I've invested so much into it, I'm not qualified to do much else now and that I'm actually very good at what I do. Again, we've discussed this out on the forum; suggest you have a read if you haven't already."
and
"First, we have to address a common misperception which we have repeatedly tried to correct on the forum: the intern year is NOT the most intense year. Thinking that it's all downhill after you complete internship is totally wrong - it's the opposite. It's intense in that you have a very steep learning curve, but WRT hours and the stress associated with carrying a lot of responsibility, your time as a trainee and lesser so as a consultant are far more demanding. Internship is a walk in the park when you look back on it.
The long and the short answer to your question is that if you want a predictably 40 hour week by the time you are 30, you might as well either a) work part time or b) aim for the "lifestyle friendly" specialties. I don't enjoy a 40 hour week, and I have been a doctor now for almost a decade. Critical care training could offer something like a 45-50 hour week, but that comes with the payoff of shift work, which essentially robs you of quality time (eg night and evening shifts ++). General practice, psychiatry and pathology would be amenable to the hours you want. Surgery and medicine would not.
Another thing worth pointing out is the massive amount of time you will have to spend studying and preparing for post graduate exams. Regardless of specialty, these represent a significant time burden (they make GAMSAT look like a piece of cake), and you're not guaranteed to pass the first go, either. You do this preparation IN ADDITION to your work - so in essence you're working full time whilst trying to study when you get home and on the weekends. You'll go into the hospital during your time off to prepare, too.
Once you are a consultant you can look for work according to the hours you want to work, but obviously it depends on job availability. If they want a full time doctor, you're looking at putting in more than 40 hours, once you factor in clinics running late, on-call, time spent after hours sorting things out and the like. They may not want to employ a part timer - it really depends on the specialty and your luck when you're out there applying.
Nutshell: if you want a predictable 9-5 job, medicine can theoretically provide that, but only if you're interested in a specialty that supports that, and only if you can tolerate the time it takes to become a fully fledged consultant (at which time you have more power/flexibility to call your hours). The time you spend training is not inconsiderable - you'll spend most of - if not all of - your twenties getting to where you want to be. There are much easier ways to become a professional. Medicine isn't particularly flexible or forgiving.
Your concern RE losing out on personal time is legitimate. I don't mean to be wholly discouraging, because this is a great job in a lot of ways, but I'd be lying if I said the personal sacrifice was always worth it.