bingoI would go rail first and try to carom the 5 ball into the 4 and make it , That way, I don't have to do anything firm with the cueball ! My goal would be to play the cueball between the pocket and the half diamond from his pocket, on his long rail, wherever that point may be with just a natural rolling shot. That way if I miss the 4 he has to get pretty lucky to get a bank . and if I make the 4 I should have the 5 straight in. Whatever happens or how I hit it ,my speed on the shot would never move the 4 ball farther from the pocket, than it is now. I hope that makes sense.
The kick behind the 4 most likely to me will leave the opponent the opportunity to move both balls out of there on his shot and you reset the tableIf I'm sure the combination goes and the five doesn't go in his pocket, I'm shooting it.
If I'm iffy on that, I like the soft hit on the 4 leaving it in the jaws (jimmyb above) or if I'm not sure I can pull that off then just kicking behind it and waiting for better shot. Especially if I'm playing a weaker player. I don't want to lose on something risky to someone I have a good chance of out moving from here on out.
If I'm playing a champion that I have little chance of out-moving, I might take the combo hoping to get lucky.
That is why you go rail first. The five stays closer to the hole and the cue ball comes to the middle of the table. Playing a straight combo is a guaranteed sellout if you don’t make the combo shooting straight at it.Play the combo and you better make it. I feel the 5 ends up nice for your opponent.