I have had the Helix Classic for a long time. I have never gotten an orgasm by itself. I can achieve it if I move it around violently with my hands and doing a circular motion. It's tough but I get there. The problem is that it is too short. I have to really push inside to reach the prostate.
That's why I would like to know which is the longest of all?
With the new one I can also try hands free, since it will reach my prostate better.
I don't know about every model, but even if I did, the stated length of each doesn't necessarily describe its inserted or effective length... that's why this is tricky to answer.
But with that said, I'll start the bidding at "Progasm". I feel subjectively like it's the longest model I have, followed by the Maximus and Eupho. All of these have a longer effective length than the Helix.
I think Vice2 is most likely the winner both in size and length.