OK, so if I'm tracking with you correctly, this P3C below I tested at 689g at 0deg yaw in 2006 at LSWT
Below that is the Cervelo test, backs my numbers up, as does the test by Andy at TAMU (on a P3T)
so, subtract 150 to 180g for the tare ... you get to 500-530g
right in step with the Shiv's numbers from A2
so...
TTX 680g
P3C 680g
Shiv 650g (corrected for +150g tare)
P4 575g