No. I have only installed latest polish firmware . Here is the link to it:
http://onyx-ereader.pl/pl/fw-boox-m92
For comarision to boxtor firmware - polish don't have multitasking, but it has less bugs, works more stable, dictionary works better, has awesome speech engine with multilingual support (I've tested both firmwares).
But If you have non arta-tech M92 you cannot install it directly. I have a method to change software both ways (special prepared firmware)