The cash-out refinance is a very powerful tool in multifamily real estate investing.
It allows you to realize some of the improved value without having to sell your property.
In many cases you can completely recapture your original investment while maintaining your cash-flow at the property.
This is great for two reasons.
First, it allows you to experience an infinite return on your remaining investment in the property.
Second, you can use the loan proceeds to investment in more real estate - further improving your cash flow.