Yay, a new rat owner! Welcome to the club.
Both of the cages you're considering are on my personal no-no list. Urine can accumulate in the shelves, plastic is extremely shreddable, the barspacing is too big [especially with females/babies, half inch barspacing is ideal.], and one of them doesn't have a very deep pan, which keeps bedding inside the cage.
If you're able to order online,
http://www.martinscages.com/products/cages/rat/ has FANTASTIC cages. Superpet cages are hard to clean and not worth the money, in my opinion. One that I see being purchased often is the Rat Manor from Petco
http://www.petco.com/product/106171/PET ... bitat.aspx and it looks pretty good. Proper barspacing, deep pan, powder coated [to prevent rusting], all around wire [nothing beats a wire cage!], and plenty of room to hang hammocks. I don't like my kids running around on the wire shelves so I bobby-pin towels down and always hang hammocks - problem solved!
The very best way to judge if the size of a cage is appopriate for your number is rats is to use a handy dandy cage calculator. I love these things.
http://www.rattycorner.com/odds/calc.shtml
http://www.huskyrat.co.uk/aboutrats/cagecalc.html
http://www.fancy-rats.co.uk/information ... alculator/
http://kristinewickstrom.homestead.com/ ... pplet.html
Do you freeze your Carefresh for 24 hours before using it? I didn't and brought mites home to my kids.. it's a very frustrating thing to deal with. ): Now I use towels to eliminate the possibility alltogether.
I think it's great that you've already had a vet jar set up for your gerbils in the past.