The intelligence aspect is heavily influenced by the choices made during game setup. Assuming that intelligence progects are not turned off altogether, the map size, chance or actuality of meeting neighbors, and you locale will influence your choice. With a large map and few players / relatively friendly players, I would probably wait on the intelligence research until I had Propulsion L3 for the cheapest engines, and perhaps Cargo L2. This would be haulted if an enemy is encountered. Also, if your locale is especially poor in resources or colonizable planets (again, game setup for what exactly a "colonizable" planet is matters), then going for a better "growth" tech (Resource Ext. or another colony tech if you are desperate) may be the only viable option. If you are cornered in and diplomacy is not working to get you out, then going for intel and hoping for a colony ship aways off or to try and subvert an established colony's populace may be the trick. If you have especially bloodthirsty neighbors, then you may need to focus on those DUCs or CSMs in order to survive the initial assualt. All in all, lots of fun choices that are too complex to give an adequate in-depth overview that covers all the possibilities.
Choose a strategy - if it works then great - if not, then try something else next time or just try it again to see if there wasn't something wrong with the situation that you tried it in rather than a flaw inherent in the strategy itself.