Hey,
we had already a nice conversation via DM but i have something to add 
The thing is:
For good reliable sensing you most likely want a Fingertip magnet.
From Dagerousthings there is only one Magnet that is suited for Fingertip Implantation - The Titan
So the Titan is the best option for sensing since it can be implanted in the Fingertip
One other location where people got sensing capabilities was -p0
Implant positions (click me)
Implant Sutra - An index of implant positions that have been discussed and/or tried
So if installing a Magnet in your Finger is not an option right now that could work, people have installed Xg3s and Titans there.
I dont think we have anyone who has both of them installed in -p0 so we have no comparisons between them 
.
Summary
If anyone wants to give me a Titan and a Xg3 V1 i can implant each in -p0 of one hand and compare them 
Since you do rock climbing i would suggest the Titan since its indestructible and smaller so i think there will be no to minimal issues with climbing (in position -p0)
Xg3 will probably also be fine but whatever happens you wont be able to destroy the titan^
And if you are not satisfied you can always get a second one in a new position 