Those cogs are primarily for BMX racing...they are the same width as Shimano splined BMX cogs. They are designed to work with a shimano type freehub body, so you shouldn't really worry about it.

I have have been using a mixture of Dimension, Shimano, and Surly cogs for years on my SSMTB with a tiny 32T chainring, and I ride up hills with it that require all the strength I can muster. The Dimensions work just as well as the Shimanos and Surly's. I mostly use Dimension 20T, 18T, and 17T cogs. I prefer the narrower cogs over the surly cogs because it gives me more freedom to tweak the chainline with thin mm spacers.

My steel freehub body still looks like new. It might dent an aluminum freehub depending on your strength and the size of your chainring. However 10 speed cassette cogs, which are commonly used with aluminum freehub bodies, are narrower still.

Edit: On second thought, I don't think any SS-specific freehubs come with a aluminum freehub body, so you probalby have nothing to worry about. And if you happen to be using a road or MTB hub with an aluminum freehub body, Novatec makes an aluminum freehub body with a single steel spline....the single steel spline adds a few grams but is sufficient to prevent notching. You could replace your freehub with this and be done with it.