I installed simple SEO mod a few weeks back and after having 900+ pages indexed for the past 6 months I am down to 235.

None of my pages are listed whatsoever.

Think this is because I arrogantly ignored your advice to install zero duplicate?

Could be, but to me 235 seems far from none.

Where you using another type of url rewriting before this ?

If not, make sure you did not implement the suggested robots.txt for the mod (as advised for such cases in the install file) and install the zero duplicate, it's the only way to have the old indexing kept.

Note as well that the zero duplicate will most likely decrease the amount of indexed pages in SE, since it will get rid of duplicates, this time, for the best

235 pages are the profiles from my primary site. Less than 10 pages to my forums are left.

URL ?