I've been sifting through plugshare etc. looking for CHAdeMO chargers near me and have found that they aren't very plentiful. Yet. The smaller J1772's are more common and *my perception* is that they are typically not useful for double charger cars. Some are, certainly, and some are - partially - but the ability to get the full 80 amps doesn't seem to be the typical situation. I've considered the possibility that the CHAdeMO adapter might be a better investment, just as you've noted!
Using the hotel example, who is going to want to walk outside in their complimentary shower robe at 1 in the morning, to plug their car in when the other guy finishes? Will the other guy be awake to unlock the charger? I think charge stations at hotels and motels should be configured to allow a full charge overnight, and thus allow the driver to leave his car in the stall while he sleeps. Playing musical chairs at 1 in the morning doesn't work for me!
I think that many people are arguing over which bad solution is better! If stopping at noon for a charge is required before reaching your destination in the evening, I don't think the single, double, or even a hypothetical triple charger system would really bring EV's into the mainstream. The Supercharger network is the solution, and I think even it will have to be improved as battery and cooling technology advances, to really make it acceptable to the masses.
J1772 charging mid-trip is still a BandAid solution in my mind, no matter whether you have one or two chargers in the car. Stopping at a Supercharger is like pulling into a full serve gas station. J1772 is more like stopping in the desert near a fuel cache situated 100 meters off the road, manually pumping a 5 gallon Jerry can full and carrying it back and forth. Having two Jerry cans makes the process twice as fast, but it still sucks.
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I have to disagree... I think the onboard charger will ultimately be sized for a reasonable charge time overnight, with the expectation that DC chargers, capable of making the 20 kW look like a hand-cranked generator, will become the mid-trip recharging solution. 20 kW is only half as bad as 10 kW, but it's still bad... ;-)
And another general comment addressed to nobody in particular... if you're travelling in the cold of winter, would you want to unplug your car at midnight to allow the next guy to plug in, or would you want to leave yours connected so it could keep the batteries warm and be toasty for your departure - without taking a chunk of your charge before you even leave the parking lot?