Hi Maximilian…I’m happy to help out if I can.
As far as whether using Isotope or Bricks AJAX filtering is better, I think it really depends on the number of objects that are being filtered. If it’s a small number (like you see on my site) then Isotope is not only instant, but is way slicker. A large number of items would be a better use for AJAx filtering, particularly if that number grows over time.