For the wiring, if you are retaining the e-chain I assume that you will either be raising the attachment point on the carriage or moving it to the left?
Either way you may need to raise and angle the other end as well (at the X motor) so the chain moves in a more graceful arc.
On mine I added a spacer between the X motor attachment plate and the right end of the e-chain.
It raises the attachment by around 1-3/4" and adds a 15 degree angle.
Works like a charm.
As for the Titan, I went straight from the carriage-mounted stock extruder to the Bowden mount on the left side of the frame.
I had been having occasional issues with the original extruder missing steps despite raising the drive current as high as I dared (I was running the hot end a bit on the cold side and it was before the Volcano block was added).
So I knew for certain that I wanted a geared (or otherwise torque multiplied) replacement.
At first I thought I'd just buy a geared stepper, but the cost and greatly increased mass were major negatives.
Then I planned to mount the Titan on the carriage.
But in the end I realized that I really, really wanted to get rid of as much mass as possible, as an experiment if nothing else.
This was because of ghosting and other artifacts that were obviously due to the huge reciprocating mass.
These could not really be tuned out unless I slowed the printing speed way down.
So it was mounted to the center side rail with about 425 mm of PTFE tube as a feed.
The only actual problem I have had with it (other than the clicking) is that the tubing slipped out of the extruder end coupling once, but I caught it in time to save the print and have since secured it in place better.
I have loosened the four bolts and snugged the gears up repeatedly.
No matter what I do, upon fast reversals such as retractions it makes noticeable noise.
It's not a whole lot of noise mind you.
But it is a noise that didn't really exist with the stock extruder.
I'm getting used to it I suppose.
I don't want to run it too tight because I don't want to risk deforming the plastic gear teeth.