What functionality is offered in the Dell OMNM system?

We have about 20 6248 switches in our entire network, so its not very big. Do we even need OMNM?

How about just using free monitoring software (theyre all over the Internet) or even something lie Solarwinds and calling it a day? That will give us all the alrm reporting we need, and when we need to manage the switch we telnet.

Does this make sense or is there some other reason that OMNM is used?

Thanks!