Wow, very ironic, but a Peacock actually caused an accident in our group ride about a week ago. A younger, less experience rider, heard a peacock screaming on a rural road and was distracted on a slight uphill as he looked over. As a result he swerved just enough to cause a chain reaction, he took out another rider, who then fell and hit the front wheel of the rider behind her, then proceeded to run over his head. He took a jolt, but said he thought for a second it was a car passing him and was relieved it was only a bike tire. He was fine, some slight bruises and rib pain, but this just shows you how quickly things can happen. If this happened to you, would this cause damage to your brittle brain?

There's some very good advice above to seriously consider. If you have trouble processing your reaction to sudden events at a higher speed, you're not only a danger to yourself, but a liability to others behind you. Things happen fast with an A ride and there's so many variables that demand a high concentration. If you sit back 4-5 feet and expect to hang on with these fast rides, I think you'll always be struggling. Unless you are in tremendous shape. The longer the ride, the more difficult this will be.

So you need to give this some serious thought. You have several options, one of which is doing mostly solo rides, or even consider time trials if your up to it. Benefits vs. Risk and only you can answer that question.