I'm no expert, only an enthusiast who can give their subjective opinions and I can't speak to how they compare to stock pads as I removed the stock pads immediately upon receiving my 400i:
However, they are extremely comfortable, bass response is very pleasurable (very, very clean bass response), they may also be slightly more isolating without sacrificing any of the soundstage.
And most noticeably what @Dopaminer
said, moving the driver away from the ear that extra mm or 2 or 3, will add bass weight.
Thanks guys! I will give them a try.