BTID will leave more money available to invest in the stock markets. Assuming you actually invest the difference every year, which takes a lot of discipline, this strategy may provide more liquid assets for the first 20 years than if whole life entered the plan.
However, by year 20 the cash value inside whole life may have yielded a 5% to 6% taxable equivalent internal rate of return (assuming a 30% tax rate and whole life purchased on healthy 30-year-old male.), comparable to that of a moderately managed portfolio over the past 20 years.
At this point the death benefit of a 20-year term policy will have expired, thus leaving you with similar lifetime values, but significantly less death benefit for heirs moving forward. In short, the BTID approach offers greater early liquidity, but at the risk of market fluctuation and a temporary death benefit.
See argument two in next blogpost.