Thats right I almost forgot about the memory card saves how your system will boot.
Even though you can do that, some games you will want in US mode and some you will want on Japanese mode.
Example of games: Samurai Shodown 1, there is no menu at all that can do language select in home mode. So you need to set it as MVS US if you want english text and un-censored mode together.
If you use the Unibios, some games let you turn on the blood after booting a game in US home mode, if you like to keep it on that mode. European Home resembles US overall. European mode is the Unibios default mode without a memory save.
I still like some things about the old debug bios though, it did make it so you had demo sound before the title screen came up in MVS mode on a AES system. Other than that, the Unibios still whips it.