Using udev as-is and device URI

[T <mlist4suntong@yahoo.com>]

Hi

I know that udev has the advantage that allowing people to write their own
rules for mounting the devices. But can I just use the udev as-is? Does
udev fully backward compatible with traditional /dev directory?

I have a Epson Stylus CX1500, which has been working fine. I used to check
the ink level with the command:

  $ escputil --ink-level --new --raw-device /dev/usb/lp0

But now, having upgraded from Sarge to Etch, the command does not work any
more. Is it because of udev or the escputil itself? Now when the command is
issued, the printer reacted with some noise then tried to print something,
then stopped. The escputil just hangs there.

Moreover, how does the device URI work?

To be specific, after upgrading from Sarge to Etch, I configured my CUPS the
Sarge way, and it works great. Then I found that there is an auto-detected
printer, so I give it a try too. However, no matter how I tweak it, it just
refuses to work. The following list is the 2 CUPS printer in my system. The
1st works, the 2nd doesn't. The only difference that I can tell now is the 
device URI. 

Please help

thanks

epson_cx1500:

Description: Epson Stylus CX1500
Location: USB Printer #1
Make and Model: Epson Stylus CX1500 - CUPS+Gutenprint v5.0.0-rc3
Printer State: idle, accepting jobs, published.
Device URI: usb://EPSON/Stylus%20CX1500

USB_Printer_1:

Description: EPSON
Location: Local Printer
Make and Model: Epson Stylus CX1500 - CUPS+Gutenprint v5.0.0-rc3
Printer State: idle, accepting jobs, published.
Device URI: epson:/dev/usb/lp0