Hello,
I don't know if any of this will help, but I had problems (and still do) with editing.
In order for my edits to work there are 2 things I must do.
1. Ensure my layer in SDE was created by manually adding the fields, and NOT by loading in a layer from shapefile or another SDE layer. It's crazy, and ESRI can't reproduce this behaviour, but it's true for me, I have to create a new feature class and add the fields one by one with ArcCatalog rather than importing the fields.
2. My layers in my MXD feeding the service must connect to SDE using an SDE service and NOT with Direct Connect.
It took me ages to work these out and get my editing working, but so long as I do the above in addition to the usual stuff then I can get it to work.
Mark.