well the CN does cost more then $70 but you aren't going to be upgradeing from one a few years down the the road either... its an investment of course. with its sturdy construction, easy assembly, bar spacing and position and of course the large doors and wheels its going to fit all your needs unless you get more then 12 rats. if you only have a few in the double though you can use the splitting ability to partition off the top or bottom for a built in hospital cage too. it also seems like it would be easy enough to modifiy for the elderly and less mobile rats as well. the down side of the CN is i don't think you can make it a triple like you can with the FNs. BUT it is going to last a long long time.
this cage you are looking at is a good cage too. but it still will have less space then the CN and will become difficult for elderly rats at some point. it also has large drops that will need to be considered and hammocks strategically placed to prevent dangerous falls. the vertical bars will limit your hammock placement as well. you will also have more doors to consider when placing toys and hammocks. you will not be able to partition any of it off for special needs which means you will need to get another cage for sickies or injured rats that need to be removed from the rest of the colony for a time to recover. you will also need another cage when your rats get too old to manage this taller one.
but with a 1/2 inch bar spacing you will be able to have babies in there. and most of the rat's life will be suitable for that cage. a hospital cage and an eventual geri cage can be picked up easily from yard sales and classifieds cheaply too. you can even get the ones that can collapse on themselves for easy storage. it is a good cage and will suit the majority of the life of your rats. it has a lot of open space which leaves you open to inventive and creative cage designs and alterations.
i still consider the CN a better investment as it can suit a wider variety of needs, but for $70 that other cage is a good buy. i guess what it comes down to in the end is if you are happy with the buy. if you do buy it but still want the CN and buy that in a few months time too... well you wouldn't really save much money that way.