Scottie:
the manouvers from the QRH you've been telling us about are indeed correct,but: the FCTM says this
'Manouvers based solely on a TA may result in reduced separation and are not recommended'
As livingdead said TACS is not accurate in azymuth
Also the TCAS/ACASII (Change 7) at response to a TA says:
" Conduct a visual seach for the intruder.If succesful,maintain visual acquisition to ensure safe separation."
As we see,no manouvre.Just look out.If it won't be safe separation ,the TA will change to RA -then ,and only then you should make the TCAS demanded vertical avoiding manouvre.
We should trust the instruments ,TCAS is one of them,we have some sad examples of not doing it.
Brgds
Alex