Please don't take this the wrong way. I am just trying to figure out what is happening here as I am interested in getting the 8S.
I am not quite sure how you were left with only 400 mb by installing just these 19 apps and 3 games. I come to 133mb for file weights.
I am not familiair enough with WP, but I assume the file weight as shown on the app store is the compressed size. Therefore assuming it is, let's say the actual size of the apps and games altogether is approx. 200-250mb depending on the compression method (e.g. winRAR can compress up to approx. 70% of the original file size).
Anyway, so let's stick with the upper limit here. 250mb for the uncompressed apps.
1,331.20 MB storage is available as per your findings.
1,331.20 - 250 = 1,081.20
After installing the apps you should be left with 1,081.20 mb of free storage. Your findings tell us then, that the system's cache (apps, games, photos, email etc) takes up 681.20mb?
It sounds to me like you had an app installed that created a huge cache. Either that or your email accounts were full of attachments? - How many email accounts did you have and how many items did you fetch for each account?
Thanks
XENOPHOS I recently had the 8S for a day until I found out how limited you were with only 1.3GB of storage. This is what I managed to install and have 400MB free.
Fabeook App - 4mb
Twitter App - 2mb
Alarm Clock - 5mb
WP Central App - 1mb
Weave - 3mb
Weather - 1mb
Bus Times App - 1mb
Reddit App - 1mb
Flixster - 1mb
Ebay - 2mb
Paypal - 6mb
Flashlight - 1mb
Remote - 2mb?
Guitar Tuner - 1mb
Sound Hound - 2mb
Cinema Times App - 1-2mb
TV Guide - 5mb
TED - 1mb
MetroTube - 1mb
Cut The Rope - 31mb
2 other small free games - say also 30mb odd each for a total of 60mb
So I got 19 apps and 3 games and have 400MB free. Now bare in mind thats not a lot and I chose not to install another 5 that I want that I use a fair bit. Now also remember all those apps will download data and cache data as you use them. So that 400MB free will go in no time at all. Thats also not accounting for any OS updates we will get in the future which will surely take up more space.
Having the SD is great for music, video and photos. But useless for apps as you cant install them on an SD card. I'd say go for the 8X or if you want a phone of similar size get the 620 once its out.