Dual chargers still take several hours to charge so not really worthwhile for "on the road" charging..
I disagree. It is true that "dual chargers take several hours to
fully charge", and that makes 22kW charging unattractive for ultra-long distance travel where your journey requires multiple full charges.
However, there aren't many such routes in the UK, and those that exist will be covered by Superchargers sooner rather than later - if you are driving 400+ miles in a one-way trip, you probably have a choice of routes and can contrive to pass a supercharger without much of a detour (as soon as there are a handful of them around).
The case where I find dual chargers useful, and don't expect Superchargers to totally solve the problem any time soon, is for day-trip journeys just beyond the range of an '85. Unless there's a traffic-free motorway direct from your home to your destination, realistically the range of an 85 already corresponds to 5 or more hours of driving - so assuming you want to spend at least some time at your destination before turning round and driving home, you are unlikely to have time/stamina to use another full charge - but another hour or two of driving is feasible. This means an hour or two of charging with dual chargers, which is feasible to spread out into meal/coffee stops. Round-trips like this are in the 100-150 miles one-way sort of distance, and contriving to pass a supercharger is likely to be a much more significant detour (until such time as there are huge numbers of Superchargers deployed), but there are enough Ecotricity (and other) rapid chargers around that you are likely to pass one or two.
For example, the other week I drove Cambridge->Brighton and back as a day trip - 239 miles, so right on the limit of a range charge, and as it happened I was getting worse-than-usual Wh/mile since it was pouring with rain. However, I stopped 20 minutes for lunch on the way there and 10 minutes for coffee on the way back, adding ~30 miles of range, and got home with 20 miles in the tank. Yesterday, I drove Suffolk->West Drayton->Cambridge; this time traffic was such that I drove more slowly and got very good Wh/mile so on reaching my last charging opportunity I didn't need to stop - but I was only comfortable planning the trip knowing that if things had worked out less well I could easily have stopped for 20 mins or so and made up the difference. With single chargers, I would have been much less comfortable.
So I think I am going to get value out of my dual chargers before they get obsoleted - and more likely obsoleted by the CHAdeMO adapter than the supercharger rollout (given that everywhere I have charged to date at 22kW I could also have charged at 50kW if I had a CHAdeMO adapter).