I've never owned a 300b amp because of the cost of the tubes. I have an El 34 amp, and tube rolling won't break my bank! But really I think that its all about the design of the amp that makes the biggest difference. Some 300B amps will outdo a El34 amp in the areas that your asking about and some EL34 amps will outdo a 300B in those same areas, depends on the design. Do you have some amps in mind? If so someone who owns one might be able to answer better.
Good Luck, TISH
Good Luck, TISH