I revisited the riptide design for one more time, this time with the intentions of simplifying the transformation so that I could incorporate a combining feature (which didn't work very well so I dropped it.
Things I like about this design over the previous one:
1. the sub mode is more compact despite having legs
2. it has an actual foot, which makes balancing the robot form easier
3. the transformation is more straight forward (just fold him up)
4. the head has more articulation
things I prefer in the original versions
1. the head is better hidden in sub mode
2. the arms are longer
3. the general proportions work better, this one looks too tall and the arms are too short
I think this is the last version, I'm going to move onto something else.