Nothing ever wrong with having 2 filters. If I were you, I would probably opt for the canister and HOB option. This gives you another filter to add to your other tank. The canister will do a great job, and the combo should have your water in great shape.
As for media for the penguins, you don't have to change the cartridge every week or so. Just cut a small slit in the top and dump out the carbon. It's not really needed anyway. So you can dump it after it gets "used up", approximately 1-2 weeks. The blue filter floss material on there will last for a lot longer, just rinse in some tank water after your water change. Important to use tank water as you don't want to kill the beneficial bacteria.
Another way to save is buying filter floss in bulk and making your own cartridges. Many ppl rip off the blue stuff once its pretty beat up, and then attach a piece of bulk filter floss to the plastic frame that's left. Here's a link to the floss I'm talking about...
That's 10 square feet, enough to make 40 or so penguin 100 size cartridges for $7.
A sponge prefilter for the intake on the penguin and/or the canister would help keep the big stuff out of the filter, but then you have to clean the prefilter.
Any way you look at it, you will have some maintenance, with the canister you will to do maint. less often but its a little more involved when you do. With the HOB you have to do maint. a little more often, but its a little easier. Sorta like 6 in one and half dozen in the other.