I am working with Impress tables for the first time, that is the reason of this
flow of issues on this matters.
When you copy an Impress table and paste it in a text document, the default
action is equivalent to the paste special "rtf formatted" action. 
In this way you get a text table, but lose all formatting of the original table
(e.g. background colors/borders of cells etc.).
If you instead choose paste special > impress 8 you get a proprietary impress
object with all the original formatting but not a text document own table.
This is inconsistent with other similar objects behaviour: e.g. when you paste a
part of a calc sheet, the "paste" action gets you a calc object, while you can
choose "paste special rtf formatted" to obtain a text doc own table (alas again
not with all formatting carried over).
I would suggest to make the "paste" behaviour consistent (i.e. with paste you
get always the original object pasted, be it a calc or impress table).
Besides, it would be nice to be able to paste an impress table in a text doc as
a text own table (i.e. via paste special rtf formatted) retaining as much
original formatting as possible.