I feel like I can chime in on this one. We have had up to 8 mice at one time. This was not our plan, but it happened. Here are somethings that I have learned from our experience.
Female mice do better with 2 other female mice for companionship.
Pet stores do not always do a good job separating their females from their males at the right point in time. We bought a pregnant female, but didn't know it until 2 weeks later.
Pregnant females tend to be a little aggressive.
Many, if not most, pet store mice carry a disease called micoplasmia (sp?). It is a respiratory disease like pneumonia. I did not know this before we bought out mice. Five out of 8 of our mice died from this. This was very sad for my dd. One mice died from tumors and the other just died suddenly. I am not sure why. We didn't even have the 3 original pet store mice for over a year. The first one died 8 months after we got her. She was the mother of the babies. We expected more life span.
We still have one little guy. He is almost 2 years old. He is one of the babies from the litter. He is great and shows no signs of respiratory problems.
Yes, mice can be stinky especially when you have 8 in 4 cages in one room. However, I do not notice the stinkiness as much with one mouse. His tank is cleaned about once a week and that is plenty. Boys tend to be a little stinkier than the girls.
All in all, I would get a mouse again. If I were to do it over, I would get ONE MALE. It is easy to take care of. There are no surprise babies. One male mouse could very happily live in a 10 gallon aquarium with a screened lid. Our guy lives in a 5 gallon critter keeper, but that is because he has always lived there. He has never tried to chew his way out of the top, but I know some do. So, I would go with the 10 gallon aquarium with the screen to and clips to keep it securely closed.
I hope that helps some.
Jennie