On the one hand, having a strong Psykana is one of our biggest advantages and getting non-Song disciplines will make us more versatile. On the other hand, it's partly because we do Songs that our Psykana is so strong (our Psykers aren't going insane all the time).
I think I'll vote for Investigate. We have a unique and potent Displine, let's develop it rather than branch out into more dangerous stuff.
While we recognize that our Protectorates may have Psykana traditions and institutions that differ from our own, and we see this as beneficial in the variety and versatility of Psychic Displines that this would grant to the Glimmering Federation and its Protectorates;
These Traditions and Institutions must exist within bounds defined herein, this for the safety and liberty of our citizens, psykers and otherwise.
These bounds are fivefold, as follow:
First, a Bound of Faith: we recognize that there can be no safe use of the Warp without the protection and blessing of the Five-in-One. Therefore, these Institutions and the psykers therein must be devoted to the Star Child.
Second, a Bound of Rights: because Psykers are equally under the light and love of the Star Child as any other of the Faithful, they must be allowed all of the rights afforded to the Faithful, within reasonable limits of public safety.
Third, a Bound of Security: that the Psychic Displines practices must be safe from Chaotic interference. If, even under the light and protection of the Five-in-One, there remain a risk to the soul of the Psyker (and those around) from the use of Psychic Displines, then they are a threat to the Sanctity of Souls and are to be struck from the records and never used, under appropriate penalty.
Fourth, a Bound of Totality: Because Psykery is as powerful to the initiated as it is dangerous to the uniniated, the Psykana Institutions must take charge of all Psykers within their Protectorate.
Fifth, a Bound of Duty: Because the Gifts of the Star Child are not to lay fallow, and because each citizen of the Federation and its Protectorates has a duty to the Faithful, it is expected of all the Psykers of the Institution to make us of their Gifts in the service of the Federation and its Protectorates.
Within these Five Bounds, may we all lift our voices into Song.