Implementation for Microchip ENC28J60 Ethernet controller

Is the software currently working with the Standard Ethershield? (W5100)

Assuming it is... Does UDP work?

Is it more reliable than the W5100?

Is the reliability of the W5100 a software issue? In that case does this library fix that problem?

Is the ENC28J60 a better shield than the standard W5100 board?
Note: I use the Mega2560 board. The ethershield is the new one with the MicroSD card.