Following Nakamura’s inspiring win today I’m wondering about some of White’s rarer sixth-move tries in the Reversed Dragon, 1 c4 e5 2 g3 Nf6 3 Bg2 d5 4 cxd5 Nxd5 5 Nc3 Nb6. Nakamura’s [u]6 e3[/u] was new to me and there don’t seem to be many games with it. It mightn’t look much, but after 6 …c5 (obviously not the only move) 7 Nge2 Nc6 8 0-0 Be7 9 f4, Naka whipped up a mighty attack against an elite opponent!

I can think of several other non-mainline plans, though some have transpositional possibilities:

I  [u]6 a4[/u], e.g. 6 …a5 7 Nf3 Nc6 8 0-0 Be7 9 d3 0-0 10 Be3 (played by Korchnoi).

II [u]6 b3[/u] Be7 7 Bb2 0-0 8 Rc1 (delaying 0-0).

III  [u]6 a3[/u] a5 7 d3 Be7 8 Be3.

IV  [u]6 d3[/u] Be7 and now:
(a) 7 Be3
(b) 7 f4
(c) 7 Nh3
(d) 7 a4

Anyone know if there’s much writing on any of these (incl. [u]6 e3[/u]) and if so where it can be found? Any views on which is most/least dangerous?