I appologize for not being able to get more involved with this discussion. I'm sick as a dog and dont really have the energy for this right now.
Im not using any fancy logic. here just is some simple math to show why BT can't be used to exactly simulate RC.
Lets look at what it takes to get 1 rune back, regardless of type (which is ok since you are trying to make BT do the same FU/B ratio as RC).
BT requires 5 charges to get 1 rune, which is 2.5 rune strikes, which is 75 RP.
RC recharges 33% of each rune on proc, so 1 proc equals 1 "rune". It has a 45% to proc on each rune strike, so to get 1 proc you would need 1/.45 = 2.222222 rune strike, which is 66.7 RP per rune returned.
To sum up:
BT = 75 RP per rune
RC = 66.7 RP per rune