No question, a 50 to 60 year-old's reaction time is slowing down, I see it in myself, it's unmistakeable.
There's very little in the airplane that needs a "quick reaction." Most of the time the best thing a pilot can do is sit on his hands and count to ten while he thinks about it, then proceed slowly and methodically. I've seen too many hotshots try to shut down the wrong engine or get too smart for their own good, reinvent he wheel. It's just not necessary.
The most dangerous thing in the cockpit is the pilot. Slow down. Age isn't a bad thing.
What we have in the crowd that's got their panties in a knot over the age issue is the "me" crowd. Gotta have it now. World revolves around them. They think they're somehow more important. Newsflash, kids; you want what the next guy has? Tough. It's not yours. The older pilot has already put in the time; he's in the position to decide to go a few more years, not you. Deal with it.
The pathetic whining about what you think is your due only speaks poorly of you, each of you. It's not your due. You don't have a right here (even your pilot certificate is a privilege). You think you're owed something? You're wrong. Get over it. You're owned nothing.
Welcome to reality. Take some prozac and move on.