Going to a concert for the opening act?

I was thinking about going to the foo fighters concert, but I don't really like them too much. But I like Rise against who will also be playing. there is also another band there who will suck *** but will probably only play a few songs. i have been to a rise against concert before and it was amazing. i am guessing RA will play 15 or so songs and FF will do about 20. but it will also be mostly FF fans there who won't be pumped as ****ing hell for RA. i need some advice to decide.