Put a shim under the envelopes on the non-flap side in tray 6 and 7 and you should be able to feed hundreds of envelopes between reloads. If they are jamming after the fuser, tape a piece of plastic or tape over the angled plastic grid just past the fuser.
If you're in the US, you might reach out to X-Digital for a refurb Xerox BW machine. You could also get a duplicator for under $5000 if the carbonless sheets do not have variable data. Duplo and Riso and Ricoh make them and they are up for sale used on eBay and other auction sites periodically...
Epson S40600 here. Really disappointed in Epson, but the machine has been reliable and the color gamut and vibrancy are excellent. A downside is that the inks scratch very easily on most substrates without lamination. Another downside is that the printer advances 12-18" of media before starting...
The on the Versant there is a high speed setting in maintenance mode that makes mixed media switching instant. Look in the control panel for something that toggles between "high speed" and "high quality mode". If you can't find it, reach out to Xerox phone support to walk you through.
MIGRATION-OPTIMIZED DIGITAL INK SYSTEMS FOR PACKAGING PRINTING
There is no such thing as a “one-size-fits-all” ink system that
suits all digital packaging applications—learn more here: Link To White Paper