Yes and no. Yes, you totally can, but you may not get ALL the benefits out of it, since Varnish and cookies aren't the best of friends. Actually this is true of all caches and certain cookies, which makes sense if you think about it.
See, when people add things to their carts, you don't want to cache that, right? So you lose a lot of the awesome power of DreamPress.
It MIGHT be just fine with your site, of course. Hard to know without looking at the site. If you'd like, I can take a look and give you some thoughts