I'm flexible.
What about just placing Creeping Doom on the Warlock Spell book list instead?
Thematic and no one has to choose it, and if they actually upgrade the spell its already there?
How about Acid Fog (nice for raiding) in place of GH or do people prefer to just have GH?
Looking for other spells, perhaps Cloudkill?
This starts getting into the Pact Known Spells pretty quick like, and a few of them imho need revising...