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Trackers can always offer less services to the end user in order to minimize server load, and be able to rent out a cheaper server, while other trackers take it upon themselves to even hire a guy in the data center to help them out specifically, due to the nature of the content provided/material on the servers.
It all comes down to how secure you want to be, and how well/how many services you'll be providing to the end user. Remember that everything a tracker does, it has to account for, from all the different incoming connections, to the routing of the tracker side of things itself, to SSL connections if the staff want to offer it, etc. It's not always a clear cut decision of "Oh, that server looks fine to me."