From my experience, it primarily involves your distributor. A weaker distributor class can get really cranky about beam lasers since it not only drains quickly, but when it does drain you can get stuck with overheating in some fighters (Vulture happens with dual c3 beams, FDL happens with dual c2 beams and c2 pulse). On a Python, Beam lasers are the best class 2 thermal option since the distributor can handle it for at least a minute or two before even noticing that they're firing. Also, beam lasers are consistently better for shields while Pulse and Burst are consistently better for hull I've noticed. Most Vulture folk go with Pulse lasers since they not only allow you to use both A5 shield and Thrusters, the damage difference isn't that big.
The short version - Wait for a Python to be relying on Beams. The post above give better explanation methinks.