The Printer Watch web page has a review of the Epson Color Stylus 600 printer. On the page he details a problem whereby the printer may fail to work if a print job is requested after TCP/IP access has been attempted. When Graeme Bennett emailed me about his page, he further suggested that this problem may affect other inkjet printers and may be specific to Mac OS 7.6.1. In that regard, Luc Wets writes that he too had problems printing with the serial Epson driver when running Mac OS 7.6.1. The problems did not occur when using System 7.5.5. According to Graeme: "Many users on Usenet are noting similar mysteries."
The Printer Watch page also described the problem with the Chooser not recognizing the Epson driver (as noted here before).