I have to put in my .02... I was skeptical. I ran into my distributor and he had a Shmitt which I bought thinking yea right it's going to replace my wool mitt. Well, I was very convinced after my first wash. So much so, I was again two days later being more observant. I am SOLD. I initially tried the white/yellow wash mitt.
The product is simply awesome. Why? For one thing it did bother me that the wool mitts did have the potential of capturing and embedding grit inside the nap. Once inside the nap it was hard to see grit inside. But I trusted the system. With the Shmitt and white foam pad, the grit & dirt stand out. I also found out that the foam pad of the Shmitt holds far more suds and water (if it kept in a horizontal position). The wool mitt has tremendous run off - which I tried to mitigate putting a grout sponge inside the mitt. The other downside to wool mitts is that after short while, then wool naps up which too much and time to either get rid of it or use it for the underbody, etc.
One more advantage is that the cleanup is very easy. You hose off the Shmitt, wring it and let it dry. My wool mitt takes more than a day to dry. I tend to let it dry completely because I like to store my mitts sealed in a ziplock baggie to reduce the potential for contamination on my paint.
After playing with the Shmitt, I found a big tip:
Detailing World
Using the two bucket method, in the rinse bucket you slide the Shmitt against the edge of the bucket so that you scrape from the tips of your fingers to your palm where the excess water/sud solution with grit falls outside your rinse bucket. Then you swirl your Shmitt a couple of times inside the rinse bucket, follow that up with scraping again on the edge of the bucket with palm first and going toward your finger tips in a wiping motion where the excess water falls into the rinse bucket. You can see on the white foam pad of the Shmitt you are free and clear of any grit. Then you re-soap your Shmitt in the suds bucket. It's fool proof.
I was so impressed with the Shmitt, I ordered the white/white wash mitt and the yellow/white interior wash mitt. I am thinking of using the white/white for paint, the white/yellow wash for wheels. And then use the interior pad for cleaning and conditioning leather.
My last point is that this is not a sponge, but a foam pad. Big difference. Also, I bought this product on my dime. No free samples and no connection with the Edge company. Just an unbiased review from my personal experience.