TAX504 - update or insert tax data row?

I'm interested to know what other organizations are doing with TAX504:  updating existing tax data row or inserting a new tax data row?

In the past we've updated existing, but with increasing usage of self-service, and the corresponding increase of some of those same employees questioning why paychecks have certain tax withholding, we are concerned about losing the "last updated by" value.  We have the audit table, but showing someone a row from that table isn't the same as a displayed page showing last updated by self-service...

Also, Rick, is there going to be a recommendation for this going forward because of the "old" and "new" W-4 data?  (And will TAX504 be ready immediately post 1/1/20 or had we best run this before 2019 ends?)