arduino mega2560: max usb baud rate

What is the maximum baud rate that the arduino mega2560 can communicate with a host software?
200kbaud and 250kbaud should work well according with the 16Mhz quartz.

I tired to figure it out by the intermediate atmega8 that does the ttl-rx-tx<>usb bridging, and did not find it.

very nice greetings,

Open the Serial Monitor. Look at the list of [u]supported[/u] baud rates.

Serial data can be transmitted at higher speeds, but with no guarantee of success.

I was talking about any host software, not the arduino host software. From what I gathered, its driver/OS dependent. On windows, the arduino mega 2560 seems to work at 250000 baud, while on linux 230400 seems to be the max not recjected by the driver, although the jitter and hence the error rate is very high. While 250000 should work much more reliable.

Honestly, if it's like that its a big mess, because then the reprap firmware I help developing cannot take advantage of full speed in any platform-compatible way.