So far so good for me on the 1601 bios for the Maximus XIII Apex. System has been really stable in stress testing and benchmarking. Even got my 5.6ghz OC profile working almost effortlessly. Nothing bad to report atm.
You are lucky, both 1402 and 1601 are broken on my M13A with a 10900k. both of those version will boot up the first time after flashing and then any successive boots just sit at the post splash screen and never boot into the OS or allow me to boot into the bios. rollback to 1301 and everything is fine, upgrade to either 1402/1601 and the systems just sits at the rog screen....