I have not switched and still, I use Markdown, too. And I agree with a lot of things @platyhsu has written. So, what’s that supposed to mean? Well, …
If you are comfortable in writing in Word or in Pages or wherever else and if your writings will never leave Word or Pages or whatever program and if you want to control 100% of the layout up to the last detail in this environment, then I agree: do not bother with Markdown for this type of writing. Do not follow the hype…
Given this scenario, Markdown might even be more work than less work. If you are a Word power user and you have everything set up properly, you will be able to get accurate DTP results that are just impossible to achieve with Markdown alone because Markdown is “just” plain text with some markup information. For accuracy, when it comes down to styles and layouts, you will have to use something that processes your Markdown writings. Depending on the tools or apps you use with Markdown, you will achieve the same accuracy as with Word or whatever, but you will have to do some more work in order to write your own templates or styles. If you want to have an individual template that is. Using Markdown with already built-in templates like in Ulysses or tools like that is very easy, though.
If you are writing something that you just need to get out of your brain and into your Mac or iPad without knowing where to go next, consider Markdown.
If you are writing something that will end up in several places at the same time like on your blog, in an email, in a Word/Pages document, in a PDF and wherever else, consider Markdown.
If you want to store text for the ages in order to get back to it in 40 years, consider Markdown.
If you want to use Markdown because “all the cool kids do”, then do not deal with it.
To me, Markdown is a nice concept to enable you getting texts out quickly and with the possibility to process them afterwards for several use cases. Markdown is nothing new. Concept-wise, it is like LaTeX and LaTeX has been around for almost 40 years now. Of course, LaTeX has a different background and a different purpose. But the concept is similar. Web writers are Markdown’s target audience. And writing for the web is just great with Markdown - even here in the Discourse forums.
Regarding the different Markdown flavours, I would recommend to just use Markdown like explained directly at the source: Daring Fireball: Markdown
This will provide you with 100% consistency across all platforms and across every app.
If this is not enough, you could use Markdown Extended in addition to Markdown:
I use Markdown Extended and I am quite pleased with it because it provides me with more possibilities than Markdown does and still, it is quite universal.
What I personally do not like very much, is to extend it even more in order to make it even “better”. For instance, Ulysses uses something they are calling Markdown XL (wich equals to Markdown plus Markdown Extended plus even more stuff). My understanding is that nobody uses Markdown XL outside of Ulysses. So, using Markdown XL may cause your writings to lose one of their biggest advantages of Markdown: universality. But that is not a real problem: just limit yourself just to Markdown or Markdown Extended in Ulysses and you are fine everywhere, too.