So, what can you actually gain from decanting a champagne? Like, with other wines, decanting champagne allows aromas in the wine to be released. This causes the champagne to become more fragrant and it can also dramatically change how your champagne tastes. Something which seems fresh and citrussy upon opening can give way to rich, earthy and all together more vinous flavours after just 10 minutes in a decanter (or even just left in a glass).
Charles Heidseick, one of my favourites of the big champagne houses, is a big advocate of decanting their champagnes. They have even teamed up with Riedel, the glassware giant, to produce a very elegant decanter. Billecart Salmon have also produced a limited edition decanter which some Searcys champagne bars in London will be using.