i would disagree, and say go with the 2215. its not that much more expensive (idk where your from or how much 1.1k is, but last time i checked the prices were pretty close)
I had a 2113 on a 10 gallon and it was perfect, i couldnt imagine it being good enough for a 17 gallon though..Yes others have had different experiences than me, but thats what this forum is for - to get diverse opinions then make your own decision.
the 2213 MIGHT be enough flow for your tank, but the 2215 WILL be enough. The extra room for media in the 2215 only helps your tank! You can always turn down the flow of the 2215, you cant turn up the flow on the 2213. Yes you COULD add a nano koralia powerhead, but that would be more expensive than just buying the 2215 upfront, plus that would be another piece of equipment in your tank and another thing that needs to be plugged into your electric.
If you go with the 2213, i would bet that within a year you wish you just shelled out the extra cash for the 2215.
All depends on your scaping and setup for the tank.
then again, i totally agree with this..