Previously I looked at other mobo bios support pages and at that time deemed ASUS had been doing AOK. Today I checked again, Gigabyte AORUS Gaming 7 X399 has 5 official updates, link
, Taichi has 9, link
, I'm counting 10 on ZE page, link
Based on say C6H/C7H experience I'd say we'll be ok. C7H "officially" gained AGESA 184.108.40.206 on 30/11/18, C6H 13/12/18. In fact a lot of the C6H owners that think the C7H has UEFI development advantage should look at the support pages more closely.
Only the C6E seems to have lag on updates much greater.
Another little known fact is how mobo makers are locked out from tweaking firmware unlike Intel, see this post
. By this I do not mean to make your compatibility issue seem smaller.
AFAIK AMD guideline is daisy chain memory topology, I would assume then the FW is tailored towards that. C6H, C6E, ZE, ZEA have T topology. From what I understand this can lengthen the tracing between IMC/DIMM, which could perhaps be unfavourable to some CPU IMC. Why I say that is I have seen some users who had the C6H, changed to another mobo (which is daisy chain) and they gained RAM MHz on same CPU/RAM. To them it seemed the C6H was "bad", to me it seemed they had an outlier CPU/setup that just favoured daisy chain. I used 2x 2700X between C6H/C7H, 2x 8GB of Samsung B die single rank/sided attained same RAM MHz. 4x 8GB was much easier to play with on C6H than C7H. Based on that experience and as TR platform is for someone needed higher "everything" vs normal consumer T topology is the right choice.
As you have dual rank RAM and due to T topology it could be worse combo than having same RAM amount but as single rank/sided dimms. For example on C6H owners that had 2x16GB fared worse than 4x8GB.
TBH 4x8GB on ZE has an advantage over same setup on C6H. TR has 2 IMC, so basically you clocking up 2 dimms per IMC, where as on AM4 it's single IMC and the 4x8GB setup each channel your daisy chaining 2 dimms.