As one who has seen many edition changes and been a veteran of a few edition wars, I have seen much, argued with many, and witnessed the result of all that effort. So in an effort to have a much smoother transition this time around, I have three things that everyone should keep in mind going forward.
1) Those That Disagree With You Are Not Your Enemy
I cannot stress this one enough. Anyone that disagrees with you is not your enemy. Treat them like you would another gamer at your table. Be nice to them. Show them the same respect that you would like to be treated with. Their opinions are formed from a culmination of their experiences, just like yours are. If someone wants something different out of D&D than you do, that’s ok. They are entitled to their opinion. Maybe the final result will be something closer to what you want; maybe it will be closer to what they want. Heck, maybe the designers will go with something totally different. We don’t know. But treating someone as the enemy can have rather hurtful consequences on real people. All concerning a pretend world. Keep that in mind when discussing the playtest on the internet.
This goes double for the way you treat employees of game companies, such as Wizards of the Coast. These are people that make an awesome game. The last thing any of us should want to do is to stifle their creativity by treating them poorly. In a world where doxxing, Gamergate, and far worse are realities, this needs to be said and kept in mind by everyone. Treat everyone like you treat your fellow gamers at your table.
2) The Playtest Version Will Be Different Than the Final Version
The playtest version is going to introduce some new and exciting concepts to the game. Some of these will absolutely work as is or need slightly tweaked before they are added to the game. Others will be great ideas that just don’t have the right feel. This is a normal and natural part of the playtest process. Express your opinions in the various surveys and online forums without hurtful language or treating anyone poorly. Again, others are not your enemy. If enough people agree with your point of view, changes will be made. The playtest version you have in front of you may be changed in a month. So keep a longer-term viewpoint in mind.
3) You Probably Won’t Like Every Change
The final version will be a mix of excellent and frustrating. Unfortunately, no two people will agree on what is excellent and what is frustrating. Myself, I feel that 5e spellcasters have too few spells. Others will argue they have an excessive number of spells. Some want more choices in their subclasses. Others want subclasses eliminated. However, I am confident that the final result will be fun for many, many people. If you find that you are not one of those people that enjoy the new edition, you still have all your 5e books, and you can keep playing that edition.
See all of JBE’s supplements at DriveThruRPG, the Open Gaming Store, and Amazon.
Jon Brazer Enterprises 
I now have in my head the need to hear Blue Oyster Cult do a song entitled “Veteran of the Edition Wars.” :D. Really enjoy your blog and your products. And those are all very good points.