If I may, possibly you could meet "in the middle".
Having BOTH diskpart and disk management could bee "too much" for a "minimal" PE, but maybe a GUI wrapping around diskpart may do.
AFAICR the Kmanpro PEpart (modified version of original tonedeaf diskpartitioner GUI) works alright (though only with the English verison of diskpart):
http://www.911cd.net...opic=21144&st=0
There is also seemingly a new *something* in development, WinFE related (OT, boy do I hate *anything* posted wthout a date ) :
http://winfe.wordpre...winfe/diskpart/
About "third party", this could be a candidate:
http://reboot.pro/to...rtition-wizard/
or this one:
http://reboot.pro/to...tarting-sector/
Back to topic, the needs in a PE 3.0 are listed here:
http://www.msfn.org/...n-gui-in-winpe/
Wonko