I know this is a old thread, but reading it...I just wanted to comment as well.
Frankly, I think ( I get it, I have gone down that path), sometimes we over think things and over do stuff. After trying everything from sumps, cannister, HOB..etc..etc..
Here is what I think is best, most practical, light on the wallet and very easy.
You want the best filter system? Go buy some filter rock such as Seachem Filter matrix for ponds. Throw it in your tank. Looks nice as some gravel looks good. There are about $20 per bucket, and each bucket treats like 100G or so. Throw in a few buckets.
Put a power head to get a decent current in your tank so the water passes over the rock. Very effective. Why? The achilles heal of any outside filter system such as sumps is no matter how big the sump is and how much media you got there, it is still restricted by the amount of water that has to pass through the pipes and come back to the main tank. Also if the there is a power outage, your not filtering anything. Cost allot too.
Using the live rock method your getting allot of the water to "touch" the rock all the time.
I moved to this method after doing salt water for fun for a while. All they use is live rock. It is the same concept.
You may want to ( I do) put a small eheim cannister filter with some sponges in there just to clean the water of any debris or poo for cosmetic reasons. I have plecos, so I do that.
As for dealing with chloromines. Frankly, I have tested my water after two weeks with no WC and the chloromines are so small. Why spend so much money creating an auto system? Just go buy a power head/water pump, attach some plastic piping you can get from Home Depot, do your WC quickly...and done. Doesn't even cost more than $80-$100one time. Get some powder prime by the bucket and that stuff will last you years. I have a 220G tank and throw in the powder right in there. A small tea spoon is more than enough. Trying to use chemicals or filters to take out chloromines I think is over kill and really not worth the money. Just do a WC.
In my 220G, I have an adult arowana, and right now about 6 large plecos (l24s, l25s..etc)....high bio load fish...and never have had a problem.
I also put in an air pump that has a backup battery that can pump for about 12 hours if power stops. I got it for like $80.
I have seen so many systems spend tens of thousands on filteration and doing auto WC...and I don't know how many times the fish still die when the power stops as the system is too automated, or something goes wrong. I saw one guy have so much stuff he actually electrocuted his fish when he was fixing something...amazing the arowana were ok after.
Just my two cents...