Weathda,
I absolutely love my Ranger 900!! I had very similar requirements as you have, and couldn't be happier with the size, quietness, how smooth it is, and the power.
Like you I was set on the Viking, until I test drove it. I left very disappointed. I just couldn't live with the noise and vibration. It didn't impress me power wise either. That said, my boss recently purchased one and seems to be pleased with it. I'm sure it's a reliable machine, but just didn't fit me well and my wife hated it.
We immediately went and drove the Ranger 900 and was sold within just a few minutes. Very little cab noise, which with two small kids, was bery important. Plenty of space for me my wife and both kids to roam around the property comfortably. I have 286 miles on it and have never left my property yet. Over 200 of those have been with all four of us in it.
Most people who look at say there's no way they could fit it where they ride. Then I take them through my trails and they change there mind. It really is nimble for its size and I put it in some tight and steep places. Rarely use 4x4, but when I do, it's a beast. I really couldn't be happier with it. No issues so far. I wouldn't worry about belt reliability. My friend has an RZR 1000 and we've abused that thing, never an issue yet. Watch YouTube videos of how people treat them, it's amazing how much abuse they will take.
There is a lot of great machines out there, their just all a little different. The Ranger was the right mix between size, sport, and work for me. Just drive them all and pick the one that fits what you want the best.
Good Luck!