If you are hove to and still making forward progress, you are not properly hove to and in really bad conditions you place both you and your crew in serious danger. Lin and Larry Pardy's book will clearly show you how, why and when to heave to, and they clearly demonstrate the various techniques that can be used with various styles of sailing vessels. It's a must have book for anyone who seriously contemplates sailing, even in relatively sheltered waters such as Chesapeake, Delaware and San Francisco bays.
Essentially, if the vessel is making forward progress, you are moving out of the protective slick created by the hull, thereby exposing the bow to knockdown waves. Same holds true if your drift is backwards, which would expose your stern quarter to a wave washing into the cockpit.
As for loss of distance toward your destination, the side drift, when properly hove to is usually less than 1 knot, and with an 8-foot diameter sea anchor, it can be as little as .1 to .3 knots in winds of 50 knots. Essentially the boat is sitting nearly dead still while you await the storm to pass. Just how long you must wait depends solely upon the size and nature of the storm itself.
For example, most regional storms usually do not last more than 24 hours. They tend to be relatively fast moving, therefore if you are hove to for the duration, and with a drift of .1 knots, your total, sideways movement will be approximately 2.4 nautical miles during the hove to period. Consequently, if you have sufficient sea room you could actually be hove to for days without drifting very far at all.
Of course, the best thing a sailor can do is try to avoid storms, but this is not always possible. The actual amount to time most spend in a storm amounts to less than 1-percent of our total sailing time. However, when you encounter than 1-percent storm, if you're not prepared it can be a life threatening experience that you'll never forget. And, in some instances, that once a year storm could end up being fatal for you and your crew. Therefore, I would suggest first purchasing the book, or better yet, purchase the combination video and book. You can take a quick glimpse of the video preview at storm tactics - Yahoo! Search Results