When it comes to the sound of your new cello, the qualities that will keep your relationship with it healthy are a big bass, good projection, and ease of playing (speed of response). Nearly everything else can be adjusted quite easily.
How not to buy a new version of your old cello.
This is one of the hardest things to do. Every interaction with a possible new cello is colored by the sound of your current cello no matter if it is good or not. Most players first words about a trial instrument are not an unbiased review. Instead, they talk about the new instrument in relation to their old instrument, sometimes …
What are your criteria?
For the professional who has likely purchased 3, and usually more, cellos in their careers, picking a lifelong cello is something that people rarely do the first time. Or the second. And very often, even the third. It all comes down to the criteria they used to make the decision.