I really like the left rock grouping, it looks really perfect IMO. I think the right rock looks a little weird though and somewhat unsettling...why is it all alone? Is it lonely way out there??
I think that you can balance it by using taller plants on the right instead of more rocks...perhaps make a little hill over there and have DHG or something taller, with HC in the middle flats.
Just my opinion
Man I really want to get one of these tanks though, they are so cool. Looking forward to the progression on this badboy, good job!