to be honest video clips are great but they are inaccurate. what sounds good on a video can end up sounding earth shatteringly loud and drone like a bitch. defo some good setup choices you picked there, all good options. best way to decide is to get to some meets. your best bet is wales as you'll have the biggest selection in the country to choose from. i run the older Invidia true dual setup. am yet to find out exactly how good it is compared to others. but its all relative. depending on your combination of mods. the abbey dyno sheets are a good starting point, they show the gains with an uprev remap and the mods used.
yes there are difference between exhausts, different bores, different setups, gases mix/don't mix, x pipes/no x pipes, the variations are quite wide.
as said in before its all personal choice. yes their are difference, but what you make in performance, you might sacrifice in noise comfort on long journeys.
custom built does off the opportunity to fine tune it to your own liking. personally if you like the bassani, then look at what carbon coops is running, its a custom build and does sound good.