I am a firm believer in the advantages of well-designed tube frames (obviously), but structural integrity should not be a problem with a well-built CMC. I've driven Gordon Nichols' Pearl, and ridden in Bill Drayer's Blackie, and both are very solid cars. With CMC/Streetbeasts cars, the quality of the build is the most important variable, and unfortunately it's often the most variable as well.
Since you say you want entry level I'll make the following suggestion: Unless you can find a CMC built by Alan Merklin, look for a used Vintage with low mileage. That's how a lot of the folks here started out, and they love their cars. You can often find something in the teens. If that's more than you want to spend right now, be willing to put some work into CMC to make it what you want. Either way, Welcome to the Madness!