Spoiler
Whacking two should always be considered whenever the opportunity presents itself, but here we get a chance to make a 5 point board and a solid 5 prime while whacking one and I think that trumps whacking two.
6/4*(2)/2*(2) may win more gammons, but our gammon value is less than usual. Were the other side of the board otherwise I'd be concerned about elmicho anchoring on the two point and causing difficulty,but with his about-to-crunch board and our abundant timing I'm not too concerned about letting him anchor.
8/4*(2)
GNUbg 4-ply:
Spoiler
This one is no contest, since the double hit/point actually wins somewhat less gammons, apart from winning a lot less games. Leaving both the 6 and 4pt open, breaking up the blockade almost completely, is just a bit too much here, even with the double whack as tactical compensation.
1. Cubeful 4-ply 8/4*(2) Eq.: +0.7526
0.8462 0.2269 0.0037 - 0.1538 0.0222 0.0009
4-ply cubeful prune [4ply]
2. Cubeful 4-ply 6/4*/2*(2) Eq.: +0.5631 ( -0.1894)
0.7666 0.2166 0.0023 - 0.2334 0.0609 0.0027
4-ply cubeful prune [4ply]