Wusthof Classics have some real limitations when it comes to putting a truly sharp edge on them and on maintaining it. They use a type of alloy which is hardened in such a way as to be very "tough" (as opposed to be "strong"). That means the edge tends to deform (too easily) rather than chip. Consequently, they dull very easily as a result of impacting the board and cutting difficult foods -- with the edge waving and rolling. On the other hand, the edges resist wear by abrasion by pretty well.
Fortunately, waving and rolling can be easily cured by correctly using an appropriate "steel,"
You're not going to do a lot of harm to a knife with that sort of pull-through sharpener but you won't do much good either. They're too "slow." Assuming your pull through is clean and funtioning it could take more than a hundred pulls to take a knife from dull to sort of sharp. That's too much work for a half-baked result, at least in my book. Nevertheless, the pull throughs do work after a fashion.
If you're using a good wood board, and not splitting chickens or doing a lot of other heavy duty work with your chef's knive (pineapples, pumpkins, etc.), you can get away with just "steeling" (i.e., using a fine textured rod hone) daily, and actually sharpening three or four times a year. I'm afraid a pull through isn't going to be much better than a steel in that way. If you want to work with a sharp knife, you're still going to have to find a way or someone to sharpenh the knife on a regular basis.
As I said, there are limits to how far you can take a Wusthof. For one thing, the edges lack "scratch hardness" and cannot be highly polished. The sliver lining there is that you don't need a series of expensive, fine stones to create a good edge.
A lot of people are intimidated by the idea of sharpening on stones because it is a skill they don't have. Basic sharpening on stones requires very much the same skills as steeling. You're better off with a simple and inexpensive, 8" Norton Combination India stone than the pull through -- and learning to use one well enough to sharpen a Wusthof is pretty easy. Around $20. When you get good at it, you can add a "hard Arkansas" for finish polishing, for another $30.
If sharpening intimidates you, and you can afford about $75, get a Chef's Choice electric sharpener. They work very well -- if not as well as a good set of stones or an "Edge Pro" -- are incredibly convenient (just leave it on the counter), and don't have much of a learning curve at all. There is a great deal of prejudice against electric sharpeners but the Chef's Choice machines really do work and will not harm your knives as long as you follow the instructions. The more expensive machines -- $120 or so -- are pretty versatile. They can sharpen scissors, repair knives which aren't too badly chipped, and take care of the "steeling" as well.
An Edge Pro is a tool and jig device of a type known as a "rod guide." It's the best of the rod guides. They are easier to learn than freen handing on stones, and do a very good job indeed. The other rod guides are better priced but are finicky and difficult to use for large, kitchen knives. Unfortunately, Edge Pros are rather expensive. $150 and up.
You might also be interested in a Spyderco "Sharpmaker" or the large Idahone "Crock Stick" set. They suffer the deficiencies as your pull through, but not quite as badly. $30 - $60.