[@WrongEndoftheRainbow]
I don't understand them at all to make any relations with them beyond using some of their artifacts.  There likely is a connection with them however, since I get a 'deal with the devil' vibe from them.

[@TheSovereignGrave]
The risk having a Tikali haven holds is that of being frequently spied on by the Silent Imperium simply because the Silent Imperium tends to assume the worst until proven other wise.  On the flip side a agent may periodically clue your faction's own intelligence services in on potential plots against your society from what they have learned elsewhere.  The Silent Imperium may secretly have a pact with Terminus but is unlikely to ever acknowledge an open alliance.  Even Tikali who decided to set up a independent home world 'prematurely' end up having the Silent Imperium spying on them to a degree.  The Dominion is still out there after all, and you never know what plots they convene to finish what they started.