I was always confused by the older posts (original version) where people played LW/ GC; as that isn't an option in EE I kept assuming they were talking about 1 character as LW and 1 as GC......the other option blows my mind.
That said, 2 LW's is the only way I have not played this game (because the damn Madora Achievement is BROKEN and I am forced to keep using her!!!!!!), but it would definitely be more challenging without the ability to overwhelm some enemies with #s.....some encounters with only 2 characters and 2 summons would be brutal.....still, pump constitution and it would be more a grind than difficult.
