you're correct in assuming that the other side of the harness would connect to the clickity bits mounting as this is still able to with stand the forces of a crash....would be a bit stupid if i didnt cos it would rip out

So yeah, it should be fine to connect it to this mounting, but i would check with a garage first just in case

Oh, and the pro of fiiting a harness is that you don't get thrwon around the car as much as with a normal seatbelt, and you havent got the possibilty of a failure of the pendulum mechanism. The con is that you havent got the same amount of freedom to move around the seat if you want to because the whole system is fixed