Spoiler
This is an interesting one for technical play. As natural as 8/4 might look, it's an error. The bot tells us two things: moving 12/11(2) is not so bad here, rkb doesn't gain much by staying back one more pip, and it's probably balanced by rkb now being able to move off the 11pt next turn with rolls containing a two.
The other thing the bot tells us is that it's good to shift here: bring the open point closer to the builders, instead of the usual moving the builders closer to the point. By playing either move 1 or move 2, the outfield point aims directly at the open spot in the homeboard; they become builders at a favourable 6-away distance. Compare to 8/4, where only an indirect 8 covers form the outfield, which would also mean leaving a shot (except for 4-4). Since high numbers likes sixes are usually the hardest to play for rkb here, it's good to turn those into good numbers. This more than compensates for the scenarios where rkb ends up with an inferior board due to the shift.
1. Rollout 6/4(2) Eq.: -0,1599
40,49 6,43 0,25 - 59,51 6,13 0,14 CL -0,2342 CF -0,1599
[ 0,10 0,18 0,05 - 0,10 0,13 0,02 CL 0,0023 CF 0,0027]
2. Rollout 12/11(2) 5/4(2) Eq.: -0,1710 ( -0,0110)
39,40 5,99 0,26 - 60,60 4,98 0,12 CL -0,2443 CF -0,1710
[ 0,08 0,18 0,09 - 0,08 0,09 0,01 CL 0,0021 CF 0,0025]
3. Rollout 8/4 Eq.: -0,1906 ( -0,0306)
38,80 5,86 0,17 - 61,20 5,39 0,13 CL -0,2630 CF -0,1906
[ 0,10 0,20 0,05 - 0,10 0,13 0,09 CL 0,0022 CF 0,0026]
4. Rollout 8/7 6/4 5/4 Eq.: -0,1913 ( -0,0314)
38,26 5,47 0,15 - 61,74 4,28 0,02 CL -0,2614 CF -0,1913
[ 0,19 0,37 0,05 - 0,19 0,15 0,02 CL 0,0042 CF 0,0049]
5. Rollout 12/11(2) 6/4 Eq.: -0,2042 ( -0,0443)
39,09 4,71 0,05 - 60,91 6,61 0,16 CL -0,2787 CF -0,2042
[ 0,19 0,29 0,46 - 0,19 0,18 0,05 CL 0,0049 CF 0,0055]
6. Rollout 12/11(2) 8/7(2) Eq.: -0,2044 ( -0,0445)
37,82 4,50 0,06 - 62,18 4,45 0,07 CL -0,2754 CF -0,2044
[ 0,18 0,25 0,15 - 0,18 0,18 0,02 CL 0,0044 CF 0,0049]
Full cubeful rollout with var.redn.
2592 or 648 games, Mersenne Twister dice gen. with seed 866958214 and quasi-random dice
Play: 2-ply cubeful prune [world class]
keep the first 0 0-ply moves and up to 12 more moves within equity 0,16
Skip pruning for 1-ply moves.
Cube: 2-ply cubeful prune [world class]