I'm running HDMU_15912_AzboxHD_OE_2659_Flash.zip on AzBox Premium Plus - so far so good ( running with Sat DVB-S ).
I've played with DOM Parition and resized some parts. Muche better now. Also removed un-unsed packs to speed up and have more free size. Removed un-used languages, and wifi as i use on cable only.
Installed MyMetrix Skin and Picons and a local XML EPG addon. Everything looks awsome.

The things i missed is a proper Diskmanager to enable and play with USB ( to move /usr partition ), and enable SWAP.

Anyway its running like a charm in Brazil ( 70W StarOne C2/C4 KU ).

BTW, i played once with openatv-5.3-azboxhd-3.9.2-20160525_azup ( i found it ) its old as the current openatv release is the same date as HDMU, but this one uses a new Kernel 3.9.2.
Well at least for me that kernel makes me feel my box was even more fast vs the current fast release i'm running, but even on openatv forum, that was the only release i found out with that kernel. It was private beta or something.

Any Chance to compile HDMU against that kernel ? or how to extract 3.9.2 updated kernel from any place to run on our HDMU ? and proper how to install would be great.

@ndminion
Using openatv release i said, FTP and Telnet was ok - with that kernel.