Another local Mogger has a 416 with the standard axle ratios and does just fine on the highway, I think he gets up to 55 miles/hr. If he had the chance (ie cash, about $4,000) I think he would have put in the higher ratios to improve his top end speed. One other thing to consider is that with a higher top end speed, you aslo get a higher bottom end speed. So there is a trade off. In the end you have to meet your greatest needs and unfoirtunately this sometime involves a compromise.
I live about one hour away from any decent 4X4 roads so I have to get on the highway. I have done it with my old 404(max 55miles/hr) and it was ok. At 110km/hr I dont save all that much time on a trip but I feel like less of an obstacle on the highway.
You can e-mail me directly if you want any further info.
gsamuelson@dccnet.com or we can keep the discussion here for all to read!