The second-gen DPT-RP1 was recently hacked and proved to be much more useful. Reports are coming in from MobileRead that someone is selling hacked DPT-RP1 writing slates on Taobao. The seller says that this device runs Android 5.1 and user can install apps, two details which appear to be confirmed by the following video:
If you watch the video you will see, among other things, Total Commander file manager and an Android web browser.
Those are not features offered on the original DPT-RP1, nor can you use the stock unit as a monitor. And yet someone has posted a video on Bilibili showing the hacked RP1 doing just that. (I can't embed the video, sorry.)
The hackers have also confirmed that the RP1 has a 2.4GHz quad-core CPU with 2GB RAM to go along with the high resolution screen (1650 x 2200). They have not, however, posted a copy of the hack so that RP1 owners could try it on their devices.
At the time hacked RP1s are only available from that one seller on Taobao (except I don't think they're selling it anymore) which is a shame because this hack more than doubles the value of the RP1.
The RP1 retails for $700 in the US. That's a lot of money for a writing slate that only supported PDFs, but if you could access the Android OS then it would easily be worth buying.