That's the strategy that Ballard took. But it seems to me that the best (and possibly most dubious) strategy, if you could do it, would be the Atwood one: write both 'mainstream' and SF novels, but deny that your SF is SF. Then you can dismiss SF and align yourself with that particular prejudice and maintain your readership. The reason this strategy is dubious is because it maintains the prejudiced marginalisation of SF by the 'mainstream': and implicitly draws the distinction good/bad, what you write/SF. It's kind of an example of 'bad faith.'
I stand corrected. :) Though to be honestI stand corrected. :) Though to be honest, words and grammar seem to me to be equivalent of paint, and then how you arrange them, and how they are performed, is a question of form. So I think you've conflated two things: the spoken word, and "Spoken Word", one we use every day, the other is a particular arrangement, with conventions, public performances and so on. So as far as Spoken Word goes, some is more poetic, and some more, um, prose-like - it is a production of spoken words which is clearly different from speech. I guess you're right though - judging an entire form is pretty silly, so I stand corrected on that. And I did like a lot of it - and really like the RRR show Aural Text.