@Kris Mo - when you refinance and take cash out, this is not considered profit (i.e. you are not paying taxes on it at all). Using your assumptions, you've correctly outlined the mechanics of a cash-out refinance. The big thing to be aware of is that if/when you go to sell the property, you have to pay taxes on your paper gain at the time of sale and pay depreciation recapture. Your taxes on sale are NOT based on the cash received at the time of sale.
Continuing with your example, lets say that you've also taken $100K of depreciation. Your current basis in the property is $100K. If you decided to sell in 5 years, it might look like this (using simple round numbers):
Sale: $350K
Debt: $250K
Basis: $50K
Depreciation Recapture (25% on $150K): $37.5K
Tax Liability (20% on $150K): $30K
Cash Proceeds: $100K
Net Proceeds: $100K - $37.5K - $30K = $32.5K
This is a lot less net cash from the sale than if you expected to just pay 20% on the $100K proceeds.
Hope this helps