If I was going to do that I'd want to run the SRM wires internally also, and they've got a fairly large connector on the end.
This isn't such an issue with the DA Di2 as you can cut and rejoin it, but the SRM harness is shielded, and (apparently, I've not seen this personally) if you cut it and rejoin it, is prone to picking up signals from other sources.
I don't know, I'd like to do it, but it seems a lot less risky to just use the Shimano frame attachment stickers as I have at the moment.
If I was going to do that I'd want to run the SRM wires internally also, and they've got a fairly large connector on the end.
This isn't such an issue with the DA Di2 as you can cut and rejoin it, but the SRM harness is shielded, and (apparently, I've not seen this personally) if you cut it and rejoin it, is prone to picking up signals from other sources.
I don't know, I'd like to do it, but it seems a lot less risky to just use the Shimano frame attachment stickers as I have at the moment.