Chris's explanation is quite thorough. Thanks, Chris.
The W5/W7 are ancestors of the current synthesizer product line. The synth products have their own voice/performance data representation which is not remotely compatible with so-called VCE files in the arranger product line. Please don't waste time on this wild-goose chase.
The QS300 is an odd critter. It was designed when Yamaha still really cared about MIDI sequencing. The QS300 is cousin to the QY series of sequencer+tone generator modules. Unfortunately, Yamaha killed this product line dead -- it was perhaps the best hardware sequencer line ever made. Owning and using a QY-70, it has its own voice data format much like a SysEx memory dump.
The W5/W7 samples and sounds probably live on in some form today. Yamaha recycles like crazy.
Hope this extra info helps -- pj