I worry about it changing the clients return.   Isn't that the whole point of locking a return in the first place?   For example,   Say you do a return and efile it and all and lock it on Feb 1st.   Since then, Lacerte has done a number of updates that can and will make calculation changes.   So if you go and unlock the return it will update the return and will be different than the originally filed return.   Then you go to performa the clients to the next year and the numbers carried over could be wrong.    It's not going to affect every single client, but you just don't know which ones.
Isn't that the point of locking a return so that when Lacerte does updates it doesn't change the numbers after you have efiled the return?  So you have what was actually filed and those numbers get performa'd over.