I have used the Torpedo as well as the Apollo's. I really like the Torpedo... but in my opinion it is of lighter service than the Apollo (that's actually one of th ereasons I like it)
I found the Torpedo to be comfortable and fun to use, it allowed a number of different hand holding positions which kept hand / arm fatigue from being a problem. I alsfound the start / stop action to be smoother.
I found that the Apollo seemed to have more power, and it seemed that it would go faster. I also found it to be very stressful on my hands, wrists, and forearms.
I suppose it depends on the intended purpose of the dpv.
Liz