Yes, as others have said, if your RRSP is too large after age 65, and especially 71, then you will pay more taxes on withdrawl than you put going in. That is a very bad investment!!
You can split income with a spouse, but realize that OAS clawback starts around 70k/yr of income, and is gone by about 90k/yr of income.
I would target 70k to 80k of income, as a couple, from RRSP, maximum, with the rest as non registered.
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But MMM made me realize that RRSP are seldom too big, because of early FIRE.
With early FIRE, you are shifting tax burden from high income years to lower income (post early FIRE) years. As long as you are taking out less than 60k a year, your taxes should be just fine, and 60k per year x 25 year (retire at age 40) is well over $1 million dollars....
So, max out RRSP early on, then when you are in mid-40's take stock of your goal, and stop contributing if warranted..