How do you get "a much better indication"?
Well on my aircraft, at least, it tells me if I am outside a guaranteed safe vertical and horizontal profile, when I have reached the MAP and shows my position on a geo-referenced approach plate.
Your other point is very interesting
: I didn't know the reason for the lack of an IAP at Egelsbach. Given the point you make, I suppose it would have made for an interesting situation had the Citation flown what I assumed to have been a home made approach and then gone missed. Would they have ended up conflicted with EDDF traffic?