I would never consider using two canisters instead of one. I use Eheim 2217's on 75 gallon tanks and find they are great. They do not make a rush of water but do a lot of what a filter is supposed to do. They can be set up with any media you choose but I find Eheim knows what they are doing far more than most of us. When you use the media they provide, in the way they have designed it to work, I would be hard pressed to say I can improve on their years of work. They have done research on a level most of us will never get done. Along the way they have gotten a good reputation for good filters. Two medium filters will cost more, make more noise, take more space and require more work. If you find the 2217 is too much filter, there is no harm done by partially closing the provided cutoffs to restrict flow. Mag drive motors of this type are not "strained" in any way by restricted flow.
I do recommend shopping around as there are times when they are on real good sales.