[Intuition]

I found my 300 Mhz O2 to be acceptable for playing with Maya 6.5 and Softimage 3.9 but it would be the slowest choice I would make.
Sometimes I see 400 mhz cpus or even whole o2s on ebay. I bought a 300mhz o2 outright back in 2009 off ebay and later a 195mhz r10k and put in a 400mhz cpu.

The 400mhz cpu was nice and made the o2 experience a bit better than even the 300mhz.

Then finally acquired an Octane and upgraded it to dual 400mhz procs and it is quite snappy for the Maya/Softimage work.

Though the Octane is much more snappy and responsive than either O2 I would say that it is nice having the O2 be so small and lightweight.
I can move around my O2 and mess with it easier. The Octane just sits where it is and I keep it in a safe spot but do not move it. Its not ridiculously heavy but it is enough for me to worry about my back to be moving it regularly. The fan on My Octane doesn't seem to make much noise such that I wonder if it is a stock fan as people have complained about Octane fans.

Overall I prefer the Octane responsiveness but the 400Mhz O2 is snappy enough I did a few Retro Tutorials on it and it shows that it works well enough.