Great points. I'm having a hard time figuring out how a mustachian could get their RRSP larger than 150k per 10k in annual spend before reaching FI. You'd need a pretty low salary I think, and I don't know if it's possible if you only contribute using the portion of your annual salary that you didn't use for expenses.
I think the best strategy is simple - max out RRSP first, then TFSA, then taxable. In retirement draw taxable first, then TFSA, then RRSP.
If you earn $70,000 per year and save the max 18% in your RRSP for 25 years, you will have $750,000 @ 6% interest. That's good for $30,000/yr for life (4% WR), or more if you increase your WR as I plan to.
As for withdrawals, I have done quite a few scenarios for tax efficiency. It seems that for early retirees (not eligible for CPP/OAS yet) the best sequence for retirement income is RRSP first, dividends from taxable second, capital gains from taxable third, and save the TFSA for later in retirement (when you are collecting CPP/OAS). This counts for my personal situation anyways and there are a few reasons for this.
1) RRSP is taxed as regular income, so it is preferable to deplete this before CPP/OAS kicks in so it doesn't run up the tax bill too high or God forbid result in clawbacks of OAS (effectively giving you a really high "real" tax rate) as I point out in #3
2) Dividends on taxable accounts are often taxed negatively at low incomes, so it works great alongside RRSP withdrawals. For example, in BC if you and your spouse each take $20,000 in RRSP withdrawals your tax rate is 7%. If you each take $15,000 in RRSP and $5,000 in eligible dividends your tax rate drops to 2.5%
3) If you wait to take your RRSP, your account balance could get very high. Example: you retire at 45 and live off TFSA and taxable until you're 65. Now you collect CPP/OAS and start drawing down the RRSP. At 45 your RRSP was worth $400,000, now its worth $1.3M because its compounded at 6% for the last 20 years. You convert to a RRIF and minimum withdrawals at 65 start at 4% (they go up quickly from there). That's $52,000 in RRIF income alone. Add CPP and OAS and you will start getting clobbered with taxes in a hurry.
4) TFSAs are great for adding to CPP/OAS income because withdrawals are not taxable. They also have the biggest benefit of growth because you don't get taxed along the way like you do with dividend income from taxable accounts. If you need more money for emergencies / vacations etc, you can always take capital gains on your taxable account. They're taxed at 50% of regular income, so if you and your spouse each take $10,000/yr in cap gains on top of $5,000 each in CPP and $5,000 each in OAS, your tax bill in BC is 3.7%. That still gets you $40,000 in combined income with a tax bill of around $1,000.
Of course these are just scenarios that I've come up with, but so far it seems like the most tax efficient method to me.