As an outside observer and a Mancunian, I would suggest that there are parts of Manchester and Salford, particularly, that are as rough and ready as any part of the Met. Having served in Paddington and Kilburn (albeit many years ago), they are certainly no different - very diverse populations and related crime - to inner city and peri-urban areas in Manchester in terms of diversity, general attitudes of population etc. Gun and knife crime is very prevalent and drugs abound and some of the worse cases of sexual grooming appear to have happened in Rochdale and surrounding areas. In Salford, there is a core of scallywags who think themselves "gangsters" and even a few middle-aged dickheads who think they are "Mister Big" - they are neither smart nor agile enough to be ahead in their game. Sadly (and Zulu' will hopefully forgive my comment) long gone are the days when if you were a scallywag in Manchester or Salford, you might meet a real "Mister Big" a 6 foot copper who would give you a pasting if you stepped out of line. The old ways were often the best
As far as Manchester is concerned as a city - it is vibrant, the people are down-to-earth and generally friendly (even to Southern Jessies) and there is so much close at hand - great coastlines - west and east, amazing countryside, and Londoners can even get to the city in about 2 hours by train. If you're a sports fan, there's a lot of football and rugby around and cricket in the summer. I live 6,000 miles away but have to come home once a year to get my fill of Manchester - it's never enough but keeps me going.
I hope you have a successful career whatever route you decide.
(and Happy New Year to everyone on the Forum)