Hi Eric, I have a Taipan 4.9 as well, and looking from your hull trim in the picture, it looks about right to me. Basically for flat water and light to moderate winds, I try and sit as far forward as possible. I find the boat "bites" upwind better and i get more height. The boat with the bow down, seems to track upwind on its own. Sitting too far back in light to moderate winds and the boat feels a little doggy. Of course if there is chop and your dolphin striker is hitting the waves, you likely want to move back a little.
However once the wind gets stronger like 18+ knots, and the settings are right, the boat seems to "plane" upwind. At this point I keep my weigh further back, right where my crew's front foot would be behind the forestay and I would be right next to my crew. So probabyl about a foot back from the forestay. Hope this helps.

Oh yeah, and I forgot, because of the hull volume, I find myself moving my weight further forward when sailing cat rigged as opposed to sloop rigged. I can see what your friend means, hoever, remember that the A class has far less hull volume and a slight shift in weight fore and aft makes a lot more difference than the Taipan when sailed one up.