The HDD? Well, Depending on your purpose. If you are on a space-tight issue or you believe the hold is no good, then you can consider one. Unfortunately, The model you asked is already encrypted which you need at least two to run safe. If I were you , I would consider that at last as the entry price is doubled even I am not asking NM series.
The company now deploys basic encryption on newer models, you can identify this by checking if there is a strange code such as PSID like the model shown.
NM (Version 4 onwards)
The company says the method they built is for fast real wipe which was found on FIPS 140-2 equipment. Of course, the models still contain the 2-stage-encryption but the basic models only contain with one random password instead of two.
Even with fast real wipe function. If there were a powerful array, then your being would be able to get back if you know the method the company used. The real question is , Is it worth to do it?