My not-a-medical-professional understanding is that emergency c-sections frequently involve a different type of incision that creates additional risk of uterine rupture during an attempted VBAC (beyond the risk already created by having had a scheduled c-section).
I asked both my old and new OBs about VBACs. My old OB gave me the stats on risk of uterine rupture with my type of incision (she was able to use the safer type), and they still scared me. She basically said that if my uterus did rupture, they had X number of minutes to get the baby out -- she didn't sound excited about trying it. My new & current OB had a similar reaction, and my impression of his view (he didn't say it in so many words) is that VBACs aren't worth the risk, and that the recent surge in VBACs has been because of insurance companies pushing them to save money (not having to pay for c-sections). My impression is that his office has seen some bad VBAC outcomes, and they don't seem in favor of it.
I personally can't handle the risk, especially after the stress of my last pregnancy, so I decided to go with a repeat c-section. Good luck -- I hope that you and your doctor make a decision you are happy with. :)