I went through all hell breastfeeding my first son, as he was so weak (born at 28 weeks), and I never made enough milk being unable to breastfeed until he was 6 weeks old.
I had to comp feed him with formula,using a mainline from nursing mothers, and a few other desperate measures, but as he also has severe projectile reflux (he could vomit milk back up at a distance of around 3 metres away from his head) feeding was "interesting " to say the least.
When he finally refused the breast totally at 8 months, I was also told my the early childhood nurse,,,,stay away from avent or the orthadontic teats. She said the old regular shaped ones were the most favourable for the sucking action that natural breast tissue allows. Apparently the orthadontic ones arent much chop either according to her.
She also said the plain cherry shaped dummies were the preferable ones to use as well.