Oh man, they are definitely worth it. I tried to give the "No RAs" a shot on my last Let's Play with the Celts. The extra gold for infrastructure/ city states by not using it on RA's can definitely help your empire, but there is a clear slow-down and the net effect had to have been negative. Now my question would be which side of the rationalism tree to go down after Secularism? It would be nice if there was a clear rule of thumb, but probably go down the left side if you have a decent amount of quality RAs being signed and you think you'll maintain them in the future? Otherwise go down the right side for more of a core science boost and more GS?