I have got a very low price DM-1801 and played with its openGD-77 firmware as I do with my two GD-77. I must say that I am enthousiastic. It has been a really nice job to be able to adapt the GD-77's firmware like that. Congratulations.
I mostly use my DM-1801 as a sensitive hotspot. For me this a major improvment compared to my jumbospot's.
Big thanks