This project gathered a good following, so I'm now wondering where I can bring it next. There are a few things to think about and some decisions to be made. The Teensy conversion should bring very interesting improvements, that could make the product worthwhile for a crowdfunding campaign, and/or make it an interestiong open source project. But this would mean leaving the Nokia part behind, as there are not many 3310 left, the display while good is still quite low res, and there may be copyright problems.
And by the way, I think that the Gabotronics Xminilab and Xprotolab are still the best choice for a device of that kind, even if they're missing the whole current and power measurements that first pushed me to this quest. http://www.gabotronics.com/oscilloscopes/xminilab-portable-oscilloscope.htm

I foresee two "extreme" paths, and a whole lot of other viable paths inbetween. The best thing would be a community effort to expand and improve the Xprotolab by porting it to the Teensys Freescale micro (or better) and designing a platform with improved input handling and features; then a plethora of devices could be made, as it happened with the Gongkai ecosystem. I would build a board for the Nokia 3310, someone could build a Fluke lookalike case, or even an oscilloscope in a watch. The easy path would involve just designing boards for the original Xprotolab micro and work with its limitations, maybe with a second micro to handle UI, battery charging etc., as it's already happening with some customer-made Xprotolab devices.

I think that the only innovation that my device brought to the table is the Nokia 3310 "integration", but in the end that's just a gimmick, a novelty. Bringing this project forward would require a great effort, and I don't know if it will be worth it. I've done 80% of the work, with 20% of the effort. Should I leave this here as a nice exercise in creativity and a fun holiday project, or should I try to bring it to the next level by working the other 80% to complete the remaining 20% of the project?