Stone wall sealants

[Robbox]

We have a stone wall house, where the side wall faces west and receives a lot of the weather. Even though the pointing is in reasonable shape, water does penetrate and ends up as damp patches.
I have seen products like Kingfisher wall sealants in use and I am impressed with the way they shed water, but I have a couple of questions.
With any pointing on a stone wall, the cement pointing 'separates' slightly from the adjacent stone over time, so if a treated wall is shedding rainwater, will not the surface water start to find its way between the pointing/stone interface and cause more problems?
Second, would the shed water not all end up at the base of the wall and have to be taken away by surface drainage? So after treatment, attention would have to applied so as not to increase surface water problems?
What are the experiences of people on this forum?

 

[Burnerman]

A product such as Johnstones Water Seal or equivalent is very effective on porous stone - but naturally enough it doesn't fill gaps at all.
Your stone should be pointed with lime mortar - which accommodates slight movement and still allows the joints to breathe.
John