I like the convex style of tamper, good tamper for the price.
Positive Product Points
Changeable pistons so it can be used in different size portafilters Good weight to it. Convex-type (See detailed commentary) Handle is about the perfect size for me.
Negative Product Points
Not the best looking tamper (see detailed) It can be considered expensive to some (but not as bad as my Reg Barber) Gets dings in it somewhat easily
Detailed Commentary
When I got my first machine I bought a no name aluminum tamper and it worked ok. There was almost no weight to it, and it was not the greatest quality as it was not perfectly smooth and it still had "casting" marks down the side of it. I suddenly decided I was rich, and bought a Reg Barber rosewood 58mm flat tamper. Baby, is it sweet to look at and use! Good weight and nice looking too! I loved this thing forever! When I was at the SCAA show in Anaheim I was "sales-pitched" by David Schoomer himself and bought the convex ergo-tamper that he touted so much. I then took it home and did a comparison for my own good. I noticed Mark already has done this for one of his articles, but this is what I found.
The handle of my ergo-tamper must be softer, because when I did the porta-tap it already has a few dings.
The convex shape did help my shots to be a little bit more fluid in the pour (I used a scale to make sure the tamp was the same). I got a darker crema when I did identical pulls. However, I didn't notice much of a flavor change. Thats a bout it. I really couldn't say if one was better then the other, but both have found a way onto my counter.