Integrate With the NMI Gateway
The NMI gateway is the largest white-label gateway supporting over 150 processors for Card and ACH. All transactions would be able to qualify for level 2 processing fees as well as 3D secure cart. NMI has what is called the gateway emulator which uses the Authorize.net code, you just need to switch the URL strings to point to NMI. This is a quick dev project for ZOHO.
I agree with this great idea. You must have to consider this Gateway and work to obtain integration between Zoho (Subscriptions) and NMI