The Magnum will shoot farther... and harder. Can you use the extra range capability? Do you need it?
The Magnum will kick much, much harder. You care? The Magnum will cost more to feed as ammo is higher in cost and reloading will require more expensive cases and more powder. You care?
Nobody can tell you which gun is best for you or which you will like better. You decide.
I am a simple man with simple tastes. I think the 7x57 is one of the finest rifle cartridges ever designed and have several rifles in this caliber. Yes, the 7mm Magnum will everything better. Do you need to do it better?
If I can't get it done with this, then I guess I don't need to get it done.