Doesn't Matter
Is there some reason you feel the need to change? Do yourself a favor, drill some holes in scrap wood. Try some in pine, oak , cherry, or what ever wood you work with. The thing you need to remember is, the old timers didn’t have two sets of drills. I have a set of Irwins, they work fine for me. As long as you keep them sharp, they will work for you. As mhiggins mentioned, the spiral on the Jennings is tighter. That doesn’t mean they don’t work any better or worse. The auger just clears the chips. If you had a set of Jennings, I would tell you to keep them. I would tell you the same thing for Irwins. The important thing is to learn to sharpen them. It doesn’t matter which name is on the bit.