What I see on the thread you link in your OP Gene is that you keep arguing with your members and insisting XF is better. It comes across like you're telling them they are wrong, old fashioned, not savvy .... No one likes that. At the same time I really understand how you feel.
OK here goes.
FORGET telling them you spent weeks designing it. If you spent weeks working on something they frind uncomfortable then you're just guilt tripping them on your fatigue!
RATION how many times you tell them XF is better on XYZ feature. They have made their own assessment and they don't think so. They need to know you respect that.
Consider that you're not only asking them to change software - how they does it. You're asking them to change attitudes too as they have decided they don't like it much - we're targeting those, not the ones who do like it.
So triage the issues where you point our XF excellence. That means out of 5 issues critiquing XF, select only 1 or 2 to say oh but XF has something nice here.
You've written ethusiastic guide paragraphs on how to do stuff - how it's lovely, easy, efficient, right there in front of you. Ration that. Keep such a poar5agraph to 2 sentences. Why? Because by saying it's right there and easy you're telling them they are stupid not to have noticed.
My apologies for straight talk.
MOST OF ALL examine the power issues here. The central one is that YOU have the power -0 they don't. This was YOUR decision - YOUR excitement - YOUR fun. They probably had no vote and no input on it.
Some of the reaction is that, though they will not say so. Translate "You jerked me into this and I didn't choose it. GAH!"
No amount of new toys, cutting edge status etc can cancel this out.
HOW TO SOOTHE THEM
Some you won't win over. Meditate on that.
Their choice.
In fact that's one way they can rebalance their lack of choice: reject you.
Some need time. The adjustments, the lack of control on the decision.
But you can do some stuff to ease it for them and for you.
Respect the whingeing! rather than arguing with it, honour it, and invite it.
You could consider a thread that positively invites what they don't like. Ventilate it.
Ask a couple of other members to help you respond maybe - and make every response sympathy without criticism of their point, or argument. Useful phrases:
"I can see what you mean."
"Hmm yes you have a point."
"It's always a bit awkward with a new system."
"I hadn't seen it that way but now you mention is .."
"You're right ..." (This one is heap big magic.)
Even better use THEIR wording in your response say you understand it.
(psst many women are often very good at this slightly empty "I see what you mean talk. Guys tend to argue more to control the other person making forceful interesting exchange but less supportive.)
Have another thread for help on how to use the new toys.
Invite members to say their favourite bits of XF.
Do NOT mix the two threads here. If they do, split their posts or move them. Otherwise it becomes an argument.
Start the plus one with no more than THREE points that first attracted you.
If no one answers for 24 hours beg someone friendly (or 2) to post on it!
Put stuff in that gives applause to some members who DO adjust.
eg thank someone/ several someones publicly for using Likes so courteously - mentioning how friendly and quick to do this is.
By featuring members who are adjusting you're constructing an ideal of members who handle it well without you lecturing on how it works.
Where whingeing leaks out elsewhere you might be able to ghetto it on the whinge thread. If not you might be able to offer the member privately the option of using the whinge thread.
Act like a calm powerful parent. You've made the decision for the family.
They need to whinge and grumble. But you've got what YOU want - if you lose traffic it'll build again because XF is so attractive. (Some of this is your own self doubt after the change kicking in! Inevitable - you're a bit tired and having your own reaction.)
Let them have their fuss. It's not going to change the decision and they know it. Their posts are not rebellious just wistful. Quite gentle really.
Keep expressing sympathy for the whinges and at the same time use XF toys to offer interesting things to connect around.
What did they most respond to before? Do that again.