The 6H30 is considered one of the least "tube" sounding tubes. That is a generalization, of course, but many people don’t like preamps that use it for that reason. Other people seek out preamps that use it. They think that it provides some of the beneficial aspects of tubes (e.g. more 3D imaging) with less of what they consider tube colorations.
Audio Research also uses the 6H30 exclusively. I haven’t heard either company’s preamps but I think they probably sound different. You’re probably better off trying to figure out the house sound of different companies’ preamps and which might appeal to you. The best way to decide is to listen to different preamps, if you can, of course. I don’t get the opportunity to listen, so I’m like you. I try to figure out how they sound by what people write about them.
Also, I like to tube roll, so that keeps me away from the 6H30.
Audio Research also uses the 6H30 exclusively. I haven’t heard either company’s preamps but I think they probably sound different. You’re probably better off trying to figure out the house sound of different companies’ preamps and which might appeal to you. The best way to decide is to listen to different preamps, if you can, of course. I don’t get the opportunity to listen, so I’m like you. I try to figure out how they sound by what people write about them.
Also, I like to tube roll, so that keeps me away from the 6H30.