Personally, I think this shot is dead on and as perfect as one is going to make it. You nailed everything here - exposure, composition and lighting. "It don't get better than this" my friend.
By the by, one misconception I might clear up for you - an old growth forest would have less undergrowth, not more. Old growth forests have quite low diversity actually, which is partly the definition of an "old growth" forest. Only very shade tolerant plants will grow from the floor in an old growth system, and often even they have a lot of trouble. Conifers, for instance (typical of a climax forest), drop fairly copious amounts of their needles on to the forest floor below. These needles are quite acidic and believe it or not, new conifers don't handle acidic soils well (at least, not this acidic). As such, nothing much grows up from under these trees, thus the trees "protect" their own space. Most other species don't like acidic soils either, so you get very little undergrowth. Fire and blow-downs change that by knocking old trees down making a clearing that now gets a lot of sunlight, allowing pioneer (sun-loving) species to move in and the cycle starts afresh.
Anyway, I'm sure that's a whole lot more than you wanted, or cared to know, but there you go. In any event, your image is beautiful. Nice work!