What timing. I was working on a blog post with a similar idea.
Of course I can't find the link to the photo, but FW had a slide on the IX Legion during their Angelus
preview a while back (I did not personally attend).
I will probably return to this post and make it 1000 times bigger, but since it's lunch break at work, I'll cut it down.
Of all the Chapters on both sides of the Eye of Terror, I think the BA are conceptually the hardest to turn into fair, balanced, table top rules. In part because I think the IX Legion's style of warfare was the "never fight fair" type of blitzkrieg. Think of it this way...to do the fluff justice, BA would be able to do the following on the tabletop:
-Turn 1 no scatter DS within inferno pistol range
-re-rollable charges from deep strike
-high-Initiative, hard-hitting melee
-consolidating towards enemies after combat, possibly getting to attack them as well
-Morale buffs to friendliest and debuffs to opponents
I mean, geez, is that's the cheesiest OP Alpha Strike formula right there. So right away you have to rework things/scale it back.
I do agree that we have an identity crisis on the tabletop: if we are supposed to be vanilla +, then we should have everything in the SM book. If we are supposed to be more distinct, then we need rules, units, and capabilities that equal or exceed what vanilla SM gets (which we all can agree we do not right now). Compare to DA and SW regarding distinct but equal.