Attorneys always suggest the safest approach.
If I understand correctly, if somebody's I-485 is denied while they're out of the US, they'd have to council process. In addition, any time they waited in the US solely on I-485 and didn't have any other status, they'd accrue unlawful presence.
Given OPs long history in the US, there's also always a chance a CBP in bad mood can treat such returning alien poorly.
Once OP gets GC, they're in much better place.
No travel = 100% no issue
Travel = Some chance of issue
Given OP already spent 13 years in the US continuously, spending another 6-12 months until GC in hand doesn't seem out of place.