No, Traditional 1080 is 4,500kbps (for streaming), the bare minimum would be 3,000. but you can think of that 3,000 the same as playing a videogame with the "bare minimum" hardware. you're going to loose all your quality and awesome graphics. i base the "traditional" on the actual video parameters and years of editing video.
720p in 3,500 vs 1080p in 3,500... 720p is going to look much better.
another factor is that twitch video box is roughly 960x540, so taking 1080 and squashing it by half makes it look bad to begin with.
so why waste time playing around with 1080?
i prefer crisp-quality over flashy words like 1080 or 60fps.
Its the same comparison as buying a Dell with an i7, sure the i7 is nice, but, every last part in that computer is garbage.
IMO, above 3,000kbps is unreasonable to subject the masses to that kind of download rate, without the option to change it (non-partners).
lets not forget, the OP is trying to remove the blurry look from their stream. the fact he is trying to stream with the range of 2,500kbps to 3,000kbps is a huge factor in his quality/clarity. At 720 this will permit him to run slower preset for that jump in clarity while having the correct kbps for the parameters of the video to be defined as "close" to HD.