The axygen ones seem to be only selling the 50 preps kit.
Strange they mention the nucleospin as complex , it is easier/faster than for example the genelute kit from sigma.
what exactly did you mean with not a great return in terms of DNA amount? (any idea how much µg? for 2ml I guess)
I've just had a look in the lab, and they were using the Nucleobond, which is (probably) different to the Nucleospin, so some of the following may not apply.
The complexity lies in the equilibration and other steps that are required. The Axygen kits only are basically just an ordinary alkaline lysis with a filtration step and a DNA column using either spin or vacuum to get the DNA onto the column. The Nucleobond ones you have to equilibrate the column before use, then drip the solution through (slow) followed by an IPA precipitation.
I don't know about the amount much, but I do know that they don't use the Nucleobond any more.