Ah, it seems I am able to bring up the menu 100 % reliably on the M4A78-EM as well by hitting and holding the shift *immediately after firmware initialization screens* (Asus’ boot graphic and ATA Security eXtension). So holding shift from power-up or from the boot graphic screen won’t work in this setup, but seems to work with others (such as my FS laptop). I’d expect it to work from power-up consistently across different setups.
Oh, but I couldn’t reproduce it on a Fujitsu Siemens Amilo M7400 laptop, so it seems to be hardware dependent.
Still present on Precise today. I’m on an Asus M4A78-EM and a PS/2-connected keyboard, if that matters.