Yes, the TGV does just take 10 minutes so significantly quicker than the shuttle if the timings work out for you... It's great, but of course if you miss it on a pre booked ticket, you're knackered.
Even pre-booking the TGV it's still expensive. When I flew, I took a print out of the TGV times with me & then just bought tickets on the day from the station at CDG. Had the timing not worked out, then I had Magic Shuttle as my fall back plan.
So in summary, cost a little more to buy on the day, but worth paying the extra for the best flexibility.
you can take a look here & get your train times & also get an idea of priceshttps://www.sncf.com/sncv1/en/passengers
As there are 5 of you, you may find booking a booking a cab might work out cheaper than 5 separate shuttle or TGV tickets... worth looking at.