DTTG: Meta Data Size (First DTTG2 question)

What is your experience with the MetaData Size (only metadata should be synced)?
Is there any possibility to influence this size?

Details:
My two DT databases have a size of ca. 1,1 GB und 4,5 GB.
It seems that the smaller DB needs about 300-350 MB storage size only for the metadata.
is this realistic?

Or may be a reason more for a new iphone in September with more space!

How many items and how many words does the database contain (see File > Database Properties)? Lots of images and PDF documents can increase the metadata size due to the thumbnails too.

Size: 1,7 GB
121.000 different, 2.563.134 total words
5 pictures
662 pdf

DTTG2 needs about 400 MB for this DB (Information from Iphone-General-Memory)

Is it possible to deactivate the generation of thumbnails? On my ipad they are looking pretty nice, but on my iphone the save of memory would have priority.