I'd agree with most of what you say there Dave. I also learnt the hard way about getting the 4th wheel out. I find the best way to use the Zip Navigator is:
1. Hold onto the handle when going up or across steep banks, especially when wet.
2. Hold on to the handle when near water, or crossing bridges.
At Maryborough, that means I use it in "non remote" mode around the 8th/9th and 16th holes.
The other issue i have is the top bag mount always falls into its lowest position - which means the bag is leaning on the soft part (and the wedge shafts) on certain bags, making it hard to pull wedges out. Ferrins has a newer version, and his has a locking mechanism that holds the top mount higher. As an interim, i use a rubber wedge to keep it up.
Even with these issues I am happy with the purchase.
On another note, we had 3 navigators in our group at RQ. Super flash!