> Would there be any problems with my older 
> projects if I remove the previous versions of winhttrack 
> that were used to create them?
No - even though the new versions are using a new cache 
format, they are able to import the old format, and update 
previously mirrored sites.

> Also is there any real downside to using 3.32 or even the 
> newer one compared to the older 3.31? 

3.31 had many bugs, especially parsing bugs. 3.32-X 
releases fixed most of them ; and the current beta 3.33-
beta fixes remaining interface (GUI) bugs such as drag&drop 
problems.