I just strung up VS gut/irukandji and coincidentally my previous string job was vs gut/4g.
From initial impressions (playing once for 2h) I can't see irukandji lasting as long as 4g.
It's very flat, had the same experience as
@happyandbob that it twists when you do the crosses.
As I didn't pay too much attention, I have some twists now which I assume might make for a quicker break.
Rexxxer is also oval but not as flattish as irukandji and works very well as a cross. It's also rather cheap here in europe so I'd rather get that.
From a pure tension maintenance standpoint I think 4g beats Rexxxer but not too crazy of a difference.
Imo 4g has a longer break in until it plays nice although that could just be a tension issue on my side.