Since it's Thursday, you've probably made the decision. Yet, I noticed that nobody has tried to crunch numbers. I thought I would do a little of that.
Vanguard says that $100,000 will buy a straight life annuity on a single 54 year old male paying $4,434 per year, increasing by a scheduled 3% per year. That's a little higher payout that the 4% SWR, but it has no opportunity for an estate, while the traditional 4% usually leaves a big estate.
So, I assumed you work for 30 years, get 4% annual raises, and try to match the DB plan by saving in the DC then buying the annuity at age 54. My calculations say you would need to earn 10.9% (nominal) to get there.
Of course, the DC plan looks better if you quit. You only need to earn 5.4% to match the benefit you'd get if you quit after 10 years, or 4.5% to match the benefit from 5 years work.
You may expect higher raises. I'm skeptical that they would continue for a lot of years, but here are the corresponding numbers for 6% annual raises: 12.9%, 5.7%, 4.6%
I'd point out that this is a pretty generous DB plan. Your employer could stop the plan relative to new contributions at any time. I don't know if they have a legal obligation to use raises you would get after they stop the plan when they calculate your benefit (the IBM people may know). If they don't, then your result is the same as if you quit voluntarily. Also, I'm assuming the age 54 retirement is available to someone who quits work early, again, I'm not sure if that is always the case.
Caveat: These numbers come from a worksheet I threw together pretty quickly. I've been known to make errors doing that. So, if you are interested in an analysis of this type I'd urge you to set up your own worksheet.