@PetrichorSquirrel one big rat is easier to buy clothes for and deal with finicky eating. Also no worries about intrarat jealousy. One big rat can go on an airplane in one pet carrier. Could be trained as emotional support animal. Lower vet bills. One big rat can experience lots of attention: read to at night, specialized education, more time at computer. One big rat can potentially have their own bedroom and time to reflect in solitude.