I don't own a 457, but own a 452 in .22LR (and have owned a few others in the past, and 455s as well) as well as a 527 in 7.62x39. For me, the switch-barrel feature on the 455/457 is useless. If as an experienced shooter you think you might grow bored of a .22 quickly, then definitely go for the 527 - I love mine, and you honestly can't go wrong with either choice. I predominately shoot rimfires, so if I had to choose only one it'd be my 452, but I'd really hate to have to make that choice. The 527 is a great gun and 7.62x39 is a much more capable round than people tend to give it credit for.