It's Strange, but...
Back over 40 years ago, when the USAF did studies on crashes during low visibility approaches, they concluded that the most critical time was when the pilot(s) transitioned from instrument flying to completing the landing visually.
For example...a standard "200 and a half approach"... You get down there on the glide path, and right at minimums, you see what you need to see to land...and with the low viz, droplets on the windscreen, etc... you crash.
Hence, the invention of the VASI.
These days, there are a number of company SOPs out there that discourage dependence on the VASI or PAPI when you're 'at crunch time'... (Couldn't resist the pun!)
This, coupled with the limitations of the VASI (e.g. does not guarantee terrain clearance beyond 4 nm, etc.) makes me wonder what good these things are anyway.
Many glide slopes (CAT I) do not give good guidance as you get closer to the touchdown...some have signal flare, etc.
Personally, I use the visual aids down low...coupled with the G/S information.... to give me a good 'gut feel' of where I should be. I do not depend on visual aids too far from the runway for reasons stated above.
In reality, there should not be a BIG difference between the electronic glide slope and the visual indicator. If there is, it should be reported.
PantLoad