I have the 4.0 EQ and love it. It's no electric motorcycle, you do have to pedal, but if feels incredibly natural and it's light enough to keep going when the battery dies and not feel like a wheelbarrow full of lead bricks. 9/10 with 1 point docked because the way the charge cord sticks into it is dumb and makes the $100+ power adaptor susceptible to damage.
Yeah, I think the main difference with the 5 is the carbon fork and the bike can do some assist adjustments where it will increment the assist up or down based on how far you tell it you are going to make sure your battery takes you the whole way, or to keep your power/heart rate or something at a set value. I don't need that stuff, but I did find my butt determined a suspension seat post was the single biggest improvement to the bike.
I've probably had the seat post for about a year. I had one before on my father's bike which I rode from time to time, but it seems they've come a long ways since then. When I put one on the Turbo Vado I fell in love with it. I used to stand up for big cracks in the sidewalk or when dropping off pavement onto a dirt path, but now I just float over all those little obstacles while continuing to pedal and without transferring a bunch of shocks straight to my sit bones. It's an odd feeling at first, but I don't feel like I gave anything up for the extra comfort: not speed, not weight, not handling... it just isolates me from small to medium sized bumps. I did have to move my rear reflector a little bit and I moved my second taillight to an under seat mount so it wouldn't interfere with the seat post. Installation was DIY and my post came with a few extra springs to tune it to the rider's weight.
