Just wanted to share our experience but my wife went SAHM not long after our first (and only, so far) was born back in August. She took full advantage of her maternity leave and state paid options, then went back to work for a couple months before giving her notice. We went through similar discussions as you beforehand and were pretty resolved on having her go SAHM, as she felt inclined to be with him as he grows up. At the same time, she's not aggressive or as inclined about wanting to work and climb the corporate ladder. She liked the people she worked with but didn't enjoy the work in general. To her, the only work she is OK doing is mindless drone work that requires little thought. Not everyone is like this, obviously :).
Anyway, we haven't regretted the decision one bit. Sure, the extra income would have been helpful but for all intents and purposes, we're fine. As far as life now, it is definitely different but in a good way. I started a new job back in January that's full time telecommute so I reap the benefits of flexibility and watching him grow up as well - at the possible expense of going insane from having virtually no face-to-face interaction (lol... we'll see). As far as for my wife, she will also tell you that being a SAHM, let alone a mother, is quite possibly the hardest thing she has ever done. So if your wife is thinking about becoming a SAHM but is also very career-driven, don't be surprised if she at some point says to you something along the lines of her preferring to go back to work... not just because she's career-driven, but because oftentimes, you hear mothers lamenting that being a SAHM is even *harder* than their former [or current] full time jobs! Of course, she could try to balance two, but it could easily get overwhelming. My wife and I discussed her doing part-time work but I think the priority at first was to have her go full-time SAHM and see how she coped with it. Right now, she's pretty busy :) We have thought about getting some help as far as child-care goes, and our parents certainly helped out during my wife's transition through quitting her previous work. But we want to avoid having to pay for any childcare. It does help that I'm working from home, so I have the flexibility to help out with things here and there. But even with that, it doesn't diminish the fact that being a SAHM is truly a full-time job with overtime; not to mention with zero income :)
Anyway, not sure if that will help any but just wanted to give some experience or perhaps food for thought as a recently new parent myself.