Thanks for telling me that about the 208b. You're right indeed. It only fits one sensor, but at least it offers it.
Logging internal resistance continuously throughout the charging cycle may not be useful, but since it's presumably automatically logged, taking a single data point per charging cycle can be used to track the degradation of the cell over time and charging cycles.
I'd be very interested in seeing how much the internal resistance, capacity and temperature changes over the course of a couple years. Even though I have the tools to do the first, I don't do it because of the extra hassle. With a device like this, I'd only have to keep a log of the order in which cells are charged.
We have to keep in mind that this is his first charger he's selling. He may ultimately end up building something like an open source hobby charger. It's not too fetched considering he's already dreaming up a 4 port nimh version that can handle different types of cells simultaneously and with greater current. I would prefer something with a built-in power supply though, even if it limits the maximum charging current.
This device doesn't exist yet. We shouldn't set limits for a device that has yet to be designed. If there are features we want in a future charger/analyzer device that is open source, then we should be giving him feedback. We can rightly complain if he refuses to implement those features. For now I'll just complain that he's not working on this device...yet.