One tiny correction - since you're five people (I think, from the way you wrote your post), there will be a small extra charge for the fifth person, but still very reasonable. It only adds 4 euros -- so 54 euros for your taxi to your lodging. That's just over 10 euros a person! It would cost you that much to schlep there on the RER and metro, and you'd be changing, walking, etc. Take a taxi from the official stand and ignore anyone inside the airport terminal (or on the sidewalks outside) who verbally ASKS you if you want to take a taxi. Follow the signs to the official stand and get in the queue!!
Not to mention if you hire a shuttle/van in advance, it's always a pain trying to meet up with them, you are worried if your flight is late or early, etc. etc. Just take the regular taxi.