Hello! i've Tried the demo version of serum before and have been thinking since about this question.
It's Goes as fallows: Can You Move The "Serum Preset folder" To Another Folder (and/or in this case, Another external Hard Drive) Without any Issues? If Not, Can You Update Serum To Add It In? I've Love to See That.
Best Wishes To: Xfer Records And the Serum Team. From: ATJF, Also Know As Alex Hood. :)