I have quite a few dictionaries where the key is a composite of several different values (mostly strings and integers). Do I implement these keys as classes (and override GetHashCode(), Equals() etc) or do I use struct instead?
ReSharper makes it easy to do the overriding, but the code looks horrible. Are there any performance implications of using a struct instead?
If your only problem is defining equality for the use in a Dictionary<TKey,TValue> then another path you may choose is implementing an IEqualityComparer<T>. This can be manually passed to the dictionary constructor and take care of equality comparisons for the TKey value without modification to the key type.
If you have the more general problem of defining equality for your composite values then I would focus on making the composite value natively support equality. Yes, defining the full set of methods necessary for equality is a pain but it's mostly boiler plate code. Getting it right is more important than whether or not the boiler plate code looks messy.