So because you don't understand them they are horrid? They have been one of our best selling items period. While they are not the fastest method of termination they do allow for what you want:
1 - install any combination of 1/0 or 4 gauge input. 1/0, 2,4, and 8 gauge outputs too....
2 - they cut down on termination points vs your method. With your ring terminal block - you added extra contact points by using a ring terminal (set screw or crimp) and if speed is an issue, try soldering and crimping 1/0 quickly. And then you have the screw point at the block. Connection points create resistance, however small or large it does happen ( a loose or poor connection obviously having higher resistance) and guys trying to get every tenth of a volt want less resistance.
3- Offer superior contact surface area compared to set screw connections. With a set screw you have one pressure point, you get about 1/2 the possible surface contact area when using a set screw. With a compression fitting you have pressure around 360 degrees of the cable.
Its all explained with images on the website:
http://www.knukonceptz.com/assets/Tech/knfhowto.pdf
This same set of directions is right on the back of the packaging that the blocks come in, we used images so you dont even need to read....LOL
The KNF-23 and KND-23 allow for several options - Each input side has two large fitting opening (ports) One port can be used for main input and the other can be used to daisy chain to another block or connect a rear bank of batteries.
The KND-23 really has no in or output since it is a common block. You can use one 1/0 in and have four 4 gauge out or if you need 8 gauge, it can accommodate three of those instead....