Although I use the Google Earth maps for the terrestrial aspects of event planning I would never trust them for something as precise as flight planning.
Case in point I have used commercial helicopter operators for joy rides 7 years now and both [Cabair and Atlas] undertook a personal site survey before operating. Those nasty HT pylons do not very threatening in the Google images but they required the use of a twin rather than a single to undertake the tasks.
As if to underline the fickleness of the images locally there is a site by the M25 where there is a giant distribution building that has been there for 5 years and just north of it there is a superstore operated by a different chain that was built three years later.
According to the current images the giant distribution building is a field of mud but the smaller store is there ... or it was 6 monhs ago! Now that cell of the on-line images has stepped back to the same dating as the giant distribution building and Tesco has simply disappeared! [That should make a lot of people happy of course ... but it is still there really!].
With that sort of spooky behavior this is certainly an unreliable resource. Maps live shows the same dated [5-7 years old] images.