I would say no. I have 7.1 and as noted above, most movies are still 5.1. The only movie I've seen in 7.1 is 3:10 to Yuma. Yes, you can notice the difference during some of the gunshot scenes. My advice, if the room is big enough and you don't care about the added expense, then go for it. I can't think of any downsides. But if you want to do it because you think there will be a huge difference from 5.1 then I'd suggest you pass. You might want to consider wiring for 7.1 though if you're building a home theatre at the moment.
If I had to do it all over again, I'd still do 7.1, but it's definitely not a dramatic difference.