First, I was able to drop in the 3.9.2 sqlite.c and sqlite.h files, build and run the app without compiler, linker or other apparent errors. Great job by dev team!
Our Windows Mobile 6.x app has been using SQLite 3.5.9, threading mode=1. I added a background thread, with its own connection to sync new records, in Sqlite DB to server and got error SQLITE_BUSY (5). Set the busy timeout and still was seeing issues. Moving to 3.9.2 the busy errors went away. Always nice. Is there any concerns I should have other than a full regression?