The main risk being that when you delete your sv.db, other addon information may go away. Things like prop protect, titles, user ratings, etc are stored in sv.db. If you delete it, all these values will reset to zero.
To edit a record:
1. Open sv.db using SQLite Database Browser
2. Go to the Browse tab.
3. Select UTime from the drop list (next to the magnifying glass)
4. Find your record (It won't have a name or steamid, only a uniqueid)
5. Double click the totaltime field. A box will pop up. Change the value therein to the number of seconds you want UTime to reflect. Then press the Apply / Close button.
6. Save the Database
7. Close SQLite Database Browser.