Let us know how you get on with that MB. That was my intial decision, but like you there were no reviews, and as it turned out no stock.
Yeah this AIO, idling at 42 Degrees I don't think that's great. I never realised that Threadripper cooling is not in the best state. After buying a Noctua was told that it will barely be able to keep it cool, forget overclocking. Looked at Full Coverage AIOs. Enermax v2 gunk up, Coolmasters klunk out. Nice, real nice. So I bought the prettiest AIO I could get, with 'Anti-Leak Tech'. The reason I have been on Air advocate for so long was fear of leaks. I can only pray.