You must get it cleaned. Chocked catalytic converter can give bad mileage and if it gets chocked 100% your car will even stop accelerating. And then some mechanics break all the things inside it which means your car will produce more pollution and will give bad mileage.
And getting it cleaned by machine is not a problem at all. Many mechanics open the cat converter and wash it which also is not an issue as well but it requires more time and must be done by some good mechanic. I got my vitz catalytic converter cleaned by the machine. They showed me with the camera and it was almost 80% chocked the time i got it cleaned. And the guy recommended that due to bad petrol in pakistan we must get it cleaned every 15000kms. Although the petrol quality is improved here now but still it is recommended by manufacturers that it must be cleaned every few thousand kms ( can vary depending on manufacturer )