Here is an Android 4.2.2 Jelly Bean rooted firmware for the PIPO U6 tablet (aka Ultra-U6) based on latest PiPO update dated 2013/12/03.

(update_U6_chinese_20131203.img / U6_software_chinese version_20131203)

Build information: 

Kernel: Linux version 3.0.36+ (root@lhh12-desktop) (gcc version 4.6.x-google 20120106 (prerelease) (GCC) ) #341 SMP PREEMPT Thu Nov 7 14:08:40 CST 2013

Android 4.2.2 JB: rk30sdk-eng 4.2.2 JDQ39 eng.root.20131203.121259 test-keys

ro.rksdk.version=RK31_ANDROID4.2.2-SDK-v1.04.00

Notes: 

- Certificate Center and original PiPO launchers have been kept in the firmware

- Certificate Center will ask for product key, which is not needed, just hit later and connect to Internet and it will be activated

- any update received thru OTA may interfere with our custom firmware, we recommend not to apply any OTA update

Custom firmware features:

• root with latest SuperSU version 1.80 (free version)
• removed most Chinese and unnecessary applications
• Google Play Store fixes so more application are visible/compatible
• updated busybox v1.21.0.git (2012-11-29)
• Unix like init.d boot scripts support, more details on init.d scripts here
• changed permissions on external sdcard to allow write access
• increased space for applications (/data partition) to 4 GB
• disabled OTA updates (may cause problems, see Notes above)
• kernel modules (cifs, tun, lan, serial, xpad) compiled by Oma & Crew RKTablets, thank guys!
• NEW!  optional ClockworkMod (CWM) Recovery easy install package

Download: kasty-pipo-u6-422-20131203-rooted4.zip

Flash with Rockchip Batch Tool version 1.7, use Restore button.

Please report any problem with this firmware, I can't verify this custom firmware works as I don't have a PIPO Ultra-U6 tablet to test the custom firmware.