How To: Replace or Clean your MacBook, MacBook Pro, or MacBook Air Keyboard Keys
Why Ask Different Stack Exchange recommends it
Apple Stack Exchange answerers point people to it when they need to remove keycaps to clean sticky or failing keys, or to rearrange keys for a layout like Dvorak.
Recommended by 3 people across 3 different months, 2012 to 2017.
What it is
A short 2011 how-to from Snazzy Labs showing how to pop off the keys on a MacBook, MacBook Pro or MacBook Air keyboard. It shows how to find the scissor mechanism under each key so you can clean or replace keycaps.
What people said
Recommends hawk · 2012-03 · Ask Different Stack Exchange · on “MacBook Pro QWERTY replacement”
I can't tell if your question is referring to the technical aspect of replacing the keys, or to general pros and cons of doing that. But one thing you might want to consider is keyboard shortcuts if you use them. Copy and Paste, Save, Select All, etc are easy to use on a QWERTY keyboard, but might not be on whatever layout you intend to switch to. Of course, getting used to an uncommon keyboard layout will also mean that you will have trouble writing on other people's QWERTY keyboards – only if you often interact with others and their computers though. As for the process of replacing the keys: there shouldn't be any problems. People do it all the time and there are plenty of guides and video
Recommends ArbiterNST · 2013-11 · Ask Different Stack Exchange · on “Rearrange keycaps on '09 MBP?”
Rather than explaining it myself through text and possibly sounding confusing, I'll just link this video: [this video] I've popped off keys before in the same way he did, and it works just fine. Obviously for rearranging your keys in a Dvorak layout, you'll want to pull up a reference image on screen of what a Dvorak keyboard looks like, in case you haven't memorized it. And then just pop all the keys off, put the mechanism parts that go under the keys back on, and then put the actual keys on in the proper arrangement. And it sounds like you've already switched your system input layout to Dvorak, but in case you haven't, it's really simple. Just go into System Preferences, then to Language & Text
Recommends Rafael Ghisleni Bagatini Carmi · 2017-07 · Ask Different Stack Exchange · on “Macbook air 2011-mid keyboard keys Q W E R T Y U I O working sporadically”
Had the same problem on my MBP13 mid 2012. After 2 months of research and almost spending $600 to replace the top case I found this video: [this video] I remove the top case of the key and gave a good clean and they start working again!!! I know this reply is for an old post but I might help other having the same issue. If this doesn't work, it might be a hardware fault :/