That said, since the PLG-150 boards load one instrument set when used in a MU128/1000/2000 (and other Yamaha gear with similar features) and another one in real synthesizers (e.g. CS-6x), and those two sets are mutually exclusive, you cannot access all instruments of each PLG-150 board at once...ever (but see those darn manuals). Of course, the sets probably have similarly named instruments, but technically they are not the same.
So gotta backpedal on this one. There is a Yamaha instrument that can actually access both instrument sets of the PLG150-VL (and possibly other PLG150 boards): the 9000 Pro (not PSR-9000) arranger keyboard.
This is a 76-key monster home keyboard that supports XG, GM, SMF, DOC, disklavier etc. formats, has aftertouch, 6 OUTs, a stereo effect return loop, MIC IN, SCSI, multiple pedal Ins, double MIDI interface, optional internal hard disk (IDE or SCSI), up to 65 Mb RAM, sampler, multi-effects, auto-accompaniment, sequencer, video OUT + PC keyboard connectors, etc. It has room for 2 PLG boards, and integrates a custom version of the PLG-100VH and has its own exclusive virtual acoustic organ flutes. To achieve accessing all the voices it uses special exclusive software editors, which fortunately are still available on the web. It only weighs 20 kg or so... 😲
...although I think it predates the "up to 9000"-meme...amusingly.