The 750 is under powered, especially to come up through any crust, and is the worst trap I have dealt with to freeze down. They don't have either the power or the jawspread to come up through much snow. They aren't a bad summertime wolf trap, if you are trapping in bare ground and mild conditions, and they are a great to bed. However I don't really like having both jaws locked down so I have to reach between them to do anything. Like clean snow out of the mechanisms. The Duke has a bigger jawspread and more power to come up through more snow and or crust, plus as a simple dog over design it is much better in freeze/thaw. You are going to have to work on the dog after a catch, most wolves will have bent that rod dog up and you will likely have to straighten on it to get it reset. They also sometimes bend up the dog rods on the 750, and they are not nearly as easy to fix in the field in order to reset.

There are better wolf traps out there than the Duke, but at it's price point it stands out against the competition. Also the Duke has thick, rounded, cast jaws that are easy on nontargets. Not that the MB 750 is, but some of the other wolf traps are.

The Duke 550s have a square pan and lighter swivels, otherwise no noticable difference. They work as well as the MBs and are cheaper.