I recently became a three furbaby household and, for me, it hasn't been that much of a difference. Yes, at first I felt a little overwhelmed...bathing, grooming and walking have had it's challenges...But, the issues have seemingly worked themselves out. I bathe all three together while my daughter, assists with the drying. I do their ears, eyes, and brushing myself. And, walking has become a sinch as they all seem to stop and squat at the same time...Although I haven't mastered keeping their chains untangles yet.
Their food expense hasn't increased by much as we all know, they really don't eat much. There are very few quarrels, if any... And, household tidyness... WELL, that's an ongoing work in progress!
So, I guess in closing, I'd have to say that it all depends on the personalities of the furbabies that you currently have and the one that your thinking about getting. Overall...The more; the merrier!!!