Problems with InsertText field and formatting

Has anyone had any problems using the InsertText field?
Specifically our organization recently abandoned the
master document feature to use the InsertText field
instead. In the beginning it worked fine, but as we start
working with larger documents (200 pages) we're noticing
some discrepancies in the formatting.

For example, graphics will resize themselves, fonts will
reverse (bold goes plain and plain goes bold), numbering
doesn't start with the correct number, and sometimes is
indented. In all these circumstances the original document
is accurate.

Checked the knowledge base with no luck so I'm counting on
someone to know the answer.

Thanks!