Yes, these guides are a little outdated, but it's still a reasonable resource to link to. Not being a Blackberry user, I wouldn't feel qualified to update the guide--perhaps another volunteer might be willing to.
You are correct in that there haven't been monumental quantum changes in Android since 4.0, but in my opinion, that's not necessarily a bad thing. Huge shifts inevitably lead to big problems with compatibility and/or glitchy untested software (see iOS7 and BB Playbook 1). I think Android hit upon a good UI and design language starting with 4.0, and has been improving it in small and not-so-small steps since then. Many changes have been under the hood, so they're not as visible.
Your dissatisfaction with the stock email client is understandable, and BB's email capabilities are hard to match by anyone, given that that has been their bread and butter since the beginning. But stock Android apps have always been fairly basic, because Android's openness gives you greater flexibility to try various other apps that are available in Google Play and elsewhere. This is also seen with music apps--historically, stock Android music players have been boring, basic, ugly affairs, but some of the 3rd party players out there are simply phenomenal
I hope you can find an ideal mobile solution if Android doesn't quite fit the bill!