Start with the list of programs
Write down every program the business depends on to get through a day. Practice-management software, accounting, the design or drawing package, document management, the point of sale, the payroll system, the industry tool nobody else has heard of. Beside each one, write where it runs today, and ask its vendor a single question: does this run from your cloud, does it need a server here, or does it do both?
That list decides the answer. Hardware follows the software, and any conversation that starts with the hardware is starting in the wrong place.
What the cloud does well
There is no box in the back room to replace, insure or trip over. Staff can work from a second site or from home without anything special. Updates and hardware failures become somebody else’s job. The cost is a monthly figure you can plan around, and adding a person is a same-morning task.
One piece of small print belongs here. A cloud service keeps your files available. Keeping a separate backup of them remains your job, because a deletion, a mistake or an encrypted file travels through a sync just as fast as it travels anywhere else.
What keeps a server in the building
A program that requires one, which is still common in dentistry, engineering, law and the trades. Very large files, such as imaging, drawings or video, where a busy office would spend its day waiting on the internet line. An internet connection that is slow or unreliable, which is a real constraint outside the city cores. A contractual or professional requirement to hold certain records on your own premises. And equipment on the floor that is driven by a computer which cannot move.
Any one of those is a good reason. Habit is not one, and neither is the fact that the current server is already paid for.
What each way costs
A server is bought once, powered and cooled, kept under warranty, and replaced on a schedule you set before it fails rather than after. Its licences renew. It needs backing up somewhere other than the room it stands in. Against that, it does not charge you monthly per person.
The cloud charges the same amount every month, forever, and that amount grows with headcount. Over a short horizon a server usually looks cheaper, and over a long one the picture depends on how many people you add. The honest comparison uses your headcount, your renewal dates and the age of what you already own.
Where most offices land
Half and half. Email, documents and the everyday files in the cloud, where they are safe from the burst pipe. One small server kept for the single program that insists on it, or for the large files. Both of them backed up, and one copy kept out of reach of the office network.