No one has really seen the new fireworks show at this point, so it's hard to say how much you'll miss if you watch the show from the F! viewing area. DLR has said that they'll be using the F! mist screens to show the projections that are normally on the castle or IaSW, so at least guests will see that part of the show. How much else you will miss is not yet know. With the first show of F! at 9:00 pm and fireworks at 9:30 pm, there is realistically no time to get anywhere else after F! ends (it's about 22 minutes in length). The new show debuts to the public next weekend, so after that we should start to see the first reviews of the show and (hopefully) reviews of the three main viewing areas (i.e., Main Street, IaSW Mall, and F! Viewing Areas).