Depending if your running just NPM and how much your doing within that, I would consider 10,000 Elements Large, but you might be able to size somewhere between Medium-Large.
Orion is the Platform that hosts all the different modules, NPM is the Network Performance Monitor. You can't run Orion Platform on it's own, it comes as part of any of the standalone modules. So if you install NPM it comes with Orion Platform. Then if you install NTA it installs and integrates with the platform.
NPM and NTA require different SQL Databases, but they can be hosted on the same SQL Instance/Server.
However by your answer can I assume you are just running NPM & NTA and nothing else? What size of license do you have? I assume SLX if you have 10,000 elements already in which case I would consider you Large for sure.
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