For 3-4 people you're better off taking a cab. It'll cost about the same and be a lot faster. The 747 futzes around wandering all around the bus station wasting a lot of time.
For one person or two do NOT user your leap card. It'll charge the full €6 fare, no discount. Instead buy a 3 day rambler which gives you 3 x 24 hours of bus service including the 747 for the least.