I can see the benefits of ECC but it generates something that in my humble view is even harder to get right - I've tried a few account numbers in his useful website - yes its balanced by error correction but I don't think its solving usability.
I'm not sure the NXT client/server is the correct place to have end users. I see everything we have now as just low-level stuff, just barely above the network itself.
What I believe needs to be done to solve usability is to have everything we're doing now abstracted away from the end user.
In the future you download your NXTransaction App from Google Play, put in your account
number edit:phrase once in the configuration section, then use a user selectable 4 or so digit pin from then on to sign transactions securely within the phone software itself.
Using NXT should look no different than using a Point-of-Sale kiosk at this point.