The problem is not so much the hole to pass the wires through but that the stock tube assembly has a channel built in for the wire allowance within the cam. This extra wire is required to allow the grip full rotation to W.O.T. There is no room for that with the G2 set-up.
I have no regrets installing the G2. It definitely smoothed out the off-idle transition. I used to get hand cramps within 30 minutes with the stock grips. I have not had one since doing this mod with the larger more ergo grips.