I don't remember being too critical of the ACE, i see it as the high-end board of choice from MSI (if there's no UNIFY or UNIFY-X at least). But only if you need some of its features, otherwise, it would be somewhat of a waste, and you might as well get a good mid-range model like a Carbon, Edge, or heck, a Tomahawk. Because even the Z790 Tomahawk would have no problem with a 13900KS. The problems will be restricted to cooling the CPU itself properly, but the Tomahawk's VRM is up to the task. Also, the performance would be identical to the Z790 GODLIKE. As long as the VRM can handle a specific CPU, and as long as you have enough PCIe lanes, ports, and functions for your use case, then all boards that fit the bill will result in the same performance numbers.
As far as four DDR5 modules running at a decent speed, yes, the high-end boards tend to have a higher signal quality, because they're using 8- or 10-layer PCBs where the RAM signals are better shielded and the signals are usually cleaner. However, they likely still use the same memory codebase for their BIOS. So even the most high-end board can't work miracles if the problem is in the memory code of the BIOS. But yes, i will agree with this thinking, that if you want to use a "borderline" RAM configuration, the more high-end board models are generally more suited to that.
With any luck, you can get DDR5-5200 stable even with four modules. I just can't help but lament what a collosal waste of money and unused features the GODLIKE is for most people, and what an obscene profit margin MSI could establish for it. And the GODLIKE buyers are usually those coming to this forum, asking how exactly to perform a BIOS update or something basic like that. I'm always willing to help everyone, no matter their level of knowledge, but sometimes it's very clear that they have no idea what their needs are and what overkill they actually purchased, simply because they thought that the priciest is also the best.
You have at least a professional justification for building a high-end system, as well as an explanation how you ended up with these highest-end models of CPU and board, which are rip-off territory. So i hope that all goes well for you, and please don't hesitate to post any questions here on how to get it working optimally. I promise i won't post more things about how i dislike the GODLIKE board or -KS CPUs, i will only try to help.