I'm working on a project I call Orthrus. I've built a prototype with an ATMega32U2, and the problem is that my software AES implementation slows it down by a factor of 5. For the application, I could sort of live with a hard disk that runs at 150 kB/sec, but 30 is just too slow to be useful.
My thinking at the moment is that if I move to the XMega32C4, I could use the hardware AES module in parallel with the I/O so that the encryption penalty isn't so bad. I have some concerns, though: The XMega support in LUFA is described as experimental. Is it deficient? Has anyone done anything with it with this chip? Also, can one use ordinary AVR ISP programming with the XMega like with the ATMega (using avrdude and a usbtiny)?