My daughters and I have kept a number of Dumbo Rats over the years. They are mellow, smart and cute companions.
The problem is they are prone to infestations and respitory issues that do not always cure, and cancerous tumors. They do not live long. Their average lifespan is 3 years.
My oldest daughter is 25 and currently has two males at the end of their lifespan. She even had the males' fixed', to extend their lifespan... but unfortunately, it had no effect on their lifespan.
Rats are the smartest of the rodents, and wonderful pets... but their short life span and health issues do not make them ideal pets. Also, call your local animal hospital and ask them how much money it costs to humanly 'put down' a rat that is suffering from, say, an inoperable tumor. You'll be unpleasently surprised how much it cost to humanely end their suffering.
BTW, rats are not good pets for people with allergies. I have allergies andbecame very allergic to rats. I no longer keep them.