As you've discovered, little data is provided by the array vendors via SNMP. In Storage Manager, we are able to pull the vast majority of our information via SMI-S. Comparing NPM and NCM, is a bit of an Apples to Oranges comparison. There is no workaround to pull data from these arrays via NPM and NCM as they do not support SMI-S data collection. I would encourage you to check out the live STM Demo, specifically the EMC Clariion in the Demo to see what data is provided out of the box.
SM talks to your arrays using various communication methods For instance, EMC Clarrion /VNX arrays being communicated over SMI-S protocol. The information we fetch from those arrays are unlimited and provide real time performance metrics, capacity information and helps you in storage forcasting. In order to obtain the information, you would need to install the EMC SMIS provider on your network (that has access to Controller IPs of the EMC Clarrion/VNX arrays). Then you shall add the Controller IPs to SMIS provider. Come back to SM and Add EMC arrays using the Provider IP Address using which we will gather the array information and present it to the users in a intuitive way. As Balki said, please have a look at Live STM demo and let us know if you have any further questions.