Maxim is touting their new MAXQ2000/3000 line, and had a benchmark graph on the cover of their mailing. Mega8 was one of the competitors. MAXQ whomped the Mega8 on the thumbnail.
Going through the full info at the link above, the Mega8 didn't do bad at all. Especially consider the iterations/$ -- the Mega8 is a $2 part; the MSP430s used are $8-10; the MAXQ $4.
I thought the 8-bit AVR fared quite well against the competition listed.