Well.... Seeing as it was I who brought up the 'true' available internal storage v App and additional Data requirements I thought it only correct to return here to back up my initial observations and concerns on the issue.
As I reported earlier in this topic although I do not play the heavy 3D games that see data downloads of 1GB+ per game, I do however have several serious medical Apps and a couple of others (SkySafari Pro to name but one) that do take up large slices of the internal storage.
Anyway, talking is one thing.... Doing is another.
So, with that I went ahead and purchased the 16GB model then proceeded to install the basic apps I would normally use which only amounted to 550MB storage.
Next up came three medical apps I could not do without; that consumed a further 2.4GB.
Then I looked at my hobbies into Astronomy and Photography which the phone was essential in having the apps installed; Bang... another 1.9GB for three titles.
Now over to the camera and although I had told the settings to store all shots on the external 64GB Card I noticed for 'Burst Shots' which I use often they can only be stored on the internal memory. As such I had to allow for 1GB to be used for the camera to act as a buffer before transferring the burst shots at the end of the day over to the external card.
Finally I have to allow for cache increases, Bluetooth transfers, other downloads, Dropbox and Google files hidden deep in the Android/Data/ etc etc, another buffer area if you wish to call, although temporary because I can clean it out as and when required but I would still need this area for apps to grow.
For this I allocated another 1GB.
So.... What was left.............2.2GB
TWO POINT TWO. Hardly what I would call the next flagship phone.
And... I must stress, I have been very restrictive in my personal choices of Apps.
If I had been given a free range I could have easily turned the total internal storage into a further 18GB of additional data.
.........I don't always get your questions right.... but you'll certainly know I've tried.
P.S. Many thanks for the Thanks votes. Thanks received are converted into a charitable donation.