The business of not knowing your deviation on the PFD/ADI outside 1 dot is a red herring. If you are flying manulaly with the F.D how have you allowed the a/c to be so far displaced?
Quite common to see this during type rating training in the simulator, and close in to the runway it gets critical if terrain near the centreline is a factor.
The HSI mode is there for an operational purpose; otherwise it would not be installed. A wise pilot utilises various display modes without being too rigid on any one.