Unless the other band is playing the same area you are, and there serious money involved, it's not worth it. A cease and desist letter from someone other than an attorney won't do anything (if you won't hire an attorney to write the letter, you won't hire an attorney to take legal action, and they will know it).
Even a cease-and-desist letter from an attorney has little weight if disregarded. The cost of litigating actual intellectual property action is exponentially higher than any potential return.
Still, the letter has two values:
- To support defendant awareness of potential wrong-doing when determining damages/civil fines at the conclusion of successful litigation
- When used as intimidation - though ignoring a cease-and-desist isn't like ignoring a subpoena or court order - it carries no criminal or civil penalties.