Bank 1-4 "Legend EP" Start with this one...

Remember that the Reface DX is a 4 operator FM synth and the Yamaha DX7 a 6 operator FM synth.
They are not compatible. It's not possible to duplicate the DX7 E.PIANO1 on a RefaceDX. Period. That doesn't mean the Reface is not capable enough to produce really good sounding typical FM E-Piano's.

The Reface DX is more compatible with the 4-operator FM synths that Yamaha produced in the past, but not completely.
Looking at the specs it has more in common with the DX9 than with for example the DX100 or TX81Z. But I expect the Reface DX to be able to create a wider range of sounds thanks to the variable feedback parameter and the effect section.

I recently ordered a Reface DX, but delivery was delayed. I will wait. I will add support for the Reface DX in my DXconvert/TXconvert toolkit.
My aim is to make it possible to convert sounds from all Yamaha's classic 4-operator FM synths that are already supported by DX/TXconvert for use with the RefaceDX. But be patient, this will take some time for me to investigate.

We'd be more interested in the sounds of today and of the future, versus looking back toward old four Operator sounds. (Although I'm sure there are many who would enjoy revisiting the classic past!) Already populating the 'test' site are scores of entirely "new" sounds utilizing the current hands-on FM interface. I'd like to see someone recreate some of these with a DX9, TX81z or a DX100 or even a DX7 for that matter... If you look at anything only through what it doesn't have, I believe you are hindered in seeing what it actually has.

Take a fresh approach, what a great way to learn about the basics of FM sound designing.

Given that on a 6-operator DX, it would take a tall stack of three to have a square wave modulate a Carrier. 2 Operators to generate the square plus the Carrier. In the reface DX a single operator can be feedback upon itself creating a square wave, so a "short stack" of two is all that is necessary to accomplish this. Not too complicated to understand, but quite a lot to explore sonically, you could spend your time trying to relive the past, I'm just recommending you learn about this new potential and start by building sounds for today and the future.

Obviously any straight conversion of a 4-Op Voice will give you a good starting place, as it will only contain one operator capable of Feedback, but folks could certainly 'improve' the sound from there.

Hey, no need to try selling me a Reface DX: I already bought one. 😀
And I *AM* interested in the new capabilities of this new DX.

I am not going to try recreating these new Reface DX sounds on the older DX synths.
What I want is to be able to (re-(use) my *HUGE* library of 4-op FM patches from the past and bring them to the present and future.
As a starting place for improvement, just like you say, but also to preserve history. My old FB01, DX100, TX7, and Korg DS-8 (yes, this is also a 4-op FM Yamaha synth internally!) are still functioning but are beginning to show their age.

I know many people who have already shown interest in my plans to support the Reface DX in my DX/TXconvert project,

BTW: The latest 4-op FM synth from the past was the V50. I once was the happy owner of one: 16-voice polyphonic, 100 ROM presets + 100 RAM patches + 100 performance memories in ROM and RAM. Compare this to the Reface DX: Only 8-voice polyphonic, and only 32 memory locations. Call me oldfashioned, but I don't see much improvement here.

As an experienced subtractive synth user I´m new to FM-synthesis and I really enjoy my new reface DX.
I´ve spent a lot of time aquiring and studying literature, videos etc. on FM-Synthesis.
Anyhow I do think it would be very helpfull to see "reface dx sample-patches" for variuous kinds of "famous" FM-sounds.
With this as a base it would be much easier to create "new modern sounds".