Buying and selling CEF's frequently can be self destructive. These are not trading stocks for most investors. They are for INCOME. Where else are you going to find a high tax free yield of 6% to 7%. That is equivalent to over 10% taxable!
These shares are a safe haven for your low risk funds. Yes, they do move with int. rates, as do all interest paying instruments, but if you do not panic and sell, they always come back. If you think you can call the int. rate moves, you can sell near the highs and buy back near the lows and pay the cap gain tax, but most holders will fare better by holding and collecting or reinvesting.