Last summer I borrowed a Vado demo bike from a local shop for a couple days so I could try it out in all my expected riding conditions, and it handled everything from paved trails to a bit of single-track. I also tried to see how fast I could get it going and did manage to break 28mph with a bit of effort and high cadence. However, I'm not really sure what exact model or model year this bike was. Being a demo, it had been stripped of everything such as fenders (if it ever had them) and whatever else was on the bars other than the old BLOKS display.With the 48t chainring it is theoretically easier to get on the 28 mph but it requires terrible effort from legs to get the cadence of 80 rpm under resistances at that speed
By the way, one reason why I actually like that the 4.0 will have a 40-tooth ring is because it will give me better climbing ability when I will leave it in Eco mode. The lowest gear combo will be 40-42, which for me works a lot better than the 48-42 combo of the 5.0. My Felt VR5 drop-bar "adventure bike" has a 46/30 chainring with a 11-32 cassette and I appreciated the 30-32 low gear on some of the steeper climbs I've done.
The downside of the 40t on the 4.0 is that I'd definitely spin-out if I get going 30+ such as on a downhill, but frankly topping 30mph on a bike makes me a bit uneasy since the consequences of crashing at such a speed are not fun!