Levinson Amp Experts, I need your help please

I was considering the Levinson 332, 333, 333.5 or 431 power amps. Is there that much of a sonic difference between these models? Will they run as hot as a Pass X-250 when pushed hard? Are there any reliability issues with any of the models? Is the .5 upgrade worth the price? Are there any other power amp options that I should consider?

Thanks and Happy Listening.