I wouldn't think BMW specific history is worth anything at that age and mileage.
If anything many dedicated indies are often far better with these cars.
Main dealers have limited exposure to N54 turbo engines IME.
Be more concerned about checking for tuning history and error codes above all else.
A 335i with fuelling or turbo issues will be a money pit of extreme dimensions.
In many respects, a car with BMW waranty makes a lot of sense in this price bracket and especially if you have little 335i / N54 model experiance to guide you.
There is a lot of rubbish out there so tread carefully.