Yes the difference in balance between the forehand and backhand is striking. I can hold the pose after hitting a backhand, but not a forehand. I also noticed that I may release the left hand too soon on a forehand, particularly when I'm running forward for a short or wide ball.
Slow motion brings out all the gory details!
PS yes, I do go to the gym regularly, for interval training and general fitness. Also worked in some tennis specific stuff. Started the Spanish RPT treadmill drills last week, and they are HARD to do! Once you get the hang of it though, it becomes less terrifying :P