An insurance agent has suggested I switch term companies every couple of years to take advantage of the company’s promotional rates in the first couple of years. Anything wrong with that?

Nothing wrong, but there is always a risk when you switch polices that you could be subject to a new contestability period.  You start a new, 2-year contestability period anytime you switch.  If you die during that 2-year period, the insurance company can (and probably will) investigate the statements you made on your application.  If you’ve given inaccurate or incomplete answers, the company may (and probably will) refuse to pay the death benefit.