Totally agree on the XL tanks (.7ml), I would say to return the one you got though, that is basically DOA. 510-T is not that tight a draw. I am not sure where you guys are buying your 510-Ts, but when I put one on an Ego battery I use a cone to tighten the draw. On my Darwin, I find the draw too airy and attach a 510-Ego adapter and screw on a cone over it.
Personally, what I don't like about the 510-T is the small tanks. I do prefer the Ego type B, with the 2ml tanks. However, if I am going to be out for a short while, I do screw on a 510-T. I find I like it better, in terms of taste, on all my variable gear. Its been a while since I used one on a non-variable device, but I think I liked the LR Ego-t better than the LR 510-t at stock voltages.