The PB1400 as well as the PM7200 with Sonnet G3 upgrade are limited to stay with System software versions below 9.2.2, because the necessary Sonnet Extension lacks support for newer Systems than version 9.1. I found no way to work around this except of checking portions of the 9.2.2 installation for compatibility, i.e. swapping and testing each Apple control panel or extension residing in the System Folder one by one. A PM7200/G3 with plenty of RAM installed this way by summer 2008 regularly works in a shop, still (if it wasn't PPC it could nicely do for the retro challenge). BTW: I also included some more recent control panels, drivers and extensions from Mac OS 8.1 into a System 7.1 installation on a PB180. Such installation of »7.1+«, »8.1+« or »9.1+« might be of interest for improved compatibility in combination with more recent software or other Macintosh computers.

However, despite running quite stable the PB1400/G3 I have has been downgraded from 9.1 to Mac OS 8.1+, because it simply is snappier to work with.