My diff is fairly tight by feel. But it's only as tight as I need to keep it from slipping.
From day one, I've found this truck to have too much steering and would have liked to put a front sway bar on. Unfortunitly, they don't make one. Initally, I increased the front spring rate to calm the steering down. Of course this sucked over bumps and jumps. Later, I figured out the a lower RC through camber links in the rear helped, purely through trial and error, so I could put the stock front spring back on. Of course the stock front spring is still way out of balance.
I never tried raising the front RC until recently, because I didn't know enough about camber links. To be honest, I really didn't notice much of a change in handling.
I think I understand what you mean as for as adding weight to the front. With more weight, I can run a heavier front and softer rear spring and still be balanced. My only concern is, right now, my car had 65% rear weight. If I add more weight to the front, even if I fix the steering problems, I'm going to have reduced forward traction down the straights. As it is now, I feel like the truck needs more forward tractions. Many times, I've lost control of the rear while I'm already half way down the straightaway.