An MTB with road tires and a hybrid like that Dew are not very different. (If you were talking about a flat bar/road bike type hybrid, I would not say that.)

And the differences are things I would argue weigh in favor of the MTB. (Sturdier, stronger wheels, etc.)

I would think about a used MTB with slicks (road tires) and maybe a different cassette (gears in the back) to give you a higher top end. (Basically, you want smaller teeth counts in the back for a higher top end.)

The MTB will hold it's value over the year or two and then if you decide to go dirt riding, you have the bike for it.