I use a variety of clear pots and like them because it allows me to see how the media is doing. Some of them do have a cone in the middle. I've not repotted them to see how they've done in comparison to others that do not have a cone. Usually if there is no cone something else is used in the middle instead like peanuts. So much depends on the media and other conditions.
In case you didn't know in general with clear pots after awhile algae can form. But I believe that is preventable with placing the clear pot in a solid one so it doesn't get light. I'm sure adding a fungicide when watering once in awhile could help prevent it too.