I'm one of those wierd people who actually enjoys trading. I initially started my trader purely to support my military character, but I've had a fair bit more fun roleplaying across Sirius as aforementioned trader.
Anyway, back on topic. Speaking for myself; I'd avoid trading factions for now because it's likely to place some limitation on range; and thus profit (and since the majority trade for money...).
Not to mention it would involve people looking into my character's background. And we can't have *that*.