My boat came similarly equipped, cutter
rig with a small staysail on a boom and high cut jib
(called a Yankee over here). Not very good performance in light air.
Adding a 130% genoa
but keeping the club footed (boom) staysail. Will use the 130 for my primary sail on roller furling/reefing and keep the yankee for heavy weather
Not sure how much benefit you would derive from a larger staysail. My main use for the staysail is to add just a little more sail area in very light airs or for quick easy sail reduction when the wind
picks up by dropping the jib
and running under main and staysail.