Does anyone have experience with "Native" adapters?

BenKepka wrote:

How well should we expect these EF-to-RF adapters to work with our current glass?

When I bought into the EOS M mirrorless system, I didn't buy any native lenses because I wasn't impressed with what was on offer at the time. I spent 2 or 3 years using nothing but my EF lenses on the EOSM via the Canon EF-to -EF-M adapter. The results were always superb. Then when the EOS M6 was released, I still used the occasional EF lens with the M-platform - but now I own three EF-M lenses... with a fourth on the way shortly.  The EF lenses I use are now usually parked on FF DSLR bodies. 
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The original EOSM bodies had a standard APS-C sensor in them which worked just fine with wider EF lenses but struggled with the light reduction involved with longer lenses.  For example, I found it hard to lock focus with the EF 100-400mmL II lens on the EOSM in daylight when the lens was extended to 400mm.  Then I bought the EOS M6 and the same lens was easily as snappy and responsive as it was on my DSLRs.  Adding a 1.4x III extender to the EF 100-400mmL II lens didn't not appear to affect performance.  I haven't used it in low light but in daylight it's superbly fast.  Faster than only DSLRs using Live View.  Finally I mounted the 2x III extender on the same lens.  Now the system was slower and slightly (only slightly) uncertain. AF was slower. Notably so.  But even with TWO extenders on the lens, spaced with an EF 12 tele-extender tube, I was still able to auto-focus on things like the Moon or the roof of a house.  I sure couldn't do that with my DSLRs.
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EOS M6 on EF 100-400mmL II lens.

EOS M6 + EF 100-400mmL II lens + EF 1.4x III extender.
Taken with the EOS M + EF 100-400mm L II + EF 2x III extender.

EOS M6 + EF 24mm f/1.4L USM II lens (note added adapter).

Taken with EOS M6 on the EF 24mm f/1.4L USM II lens.

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This is just my own opinion but if the shots below portray the performance of EF lenses on an EOS R body, then I'm convinced that my own EF lenses will do a great job on the same new body via the adapter.  It's good to see some early results.  There's a small part of me wondering if I ought to part with at least a handful of my EF lenses (eg 50mmL and 24-105L) and buy up the new RF versions instead.  The samples from those RF lenses are really nice.
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3x  Samples below from DPreview taken with the EOS R + EF lenses...
I noticed that more images are showing up her from DPREVIEW's recent uploaded samples from the new EOS R system and they've surprised me by adding a few photographs taken with the EF adapters on the EOS R camera. The resulting images look quite clean and sharp and don't appear to have been edited yet.  From Canon's own statements this week I understand that the image quality should not be affected and the responsiveness of the EF lenses ought to be identical (or very close) to the performance endured on the DSLRs with EF mounts.  Noting of course that the EOS R has one of the newer DPAF sensors - which certainly aids in accurate AF.
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EOS R + Canon EF 70-200mm F2.8L IS III USM

EOS R + Canon EF 100-400mm F4.5-5.6L IS II USM

EOS R + Canon EF 600mm f/4.0L IS II USM