There's a youtube video on this :
https://www.youtube.com/watch?v=TR82aPyigMc
I did some math, and it boils down to what percentage of your time is spent on cool-down.
@12.9sec : 43% beam, 31% Pulse - beam starts recharge
@23.9sec : 43% beam, 57% Pulse - pulse starts recharge, beam finishes recharge
@34.9sec : 80% beam, 57% Pulse - pulse finishes recharge
@36.8sec : 86% beam, 62% Pulse - beam starts second recarge
@47.8sec : 86% beam, 88% Pulse - beam finishes second recharge
@58.8sec : 122% beam, 114% Pulse - pulse starts second recharge
@60.7sec : 129% beam, 114% Pulse - beam starts third recharge.
As you can see: they leap-frog as combat continues through drain and recharge cycles. The shorter the recharge (as a percentage of total time), the better beam does; the longer the recharge (as a percentage of total time), the worse beam does. So a 1 sec recharge would make the beam the better weapon and a 60 second recharge would make the pulse the better weapon. At the 11sec quoted: It's something of a wash in most combat.
So, I tried this at home with my Vulture (A power plant, single beam laser), and I have something around a 30 sec fire time with my (normal) 4-pips to weapons, and an 11 sec recharge. What I don't know is how long the pulse lasers would work like that. If they merely doubled: then the beam weapon would be better; but since I assume weapons recharge during fire, the math is more complex (indeed; pulse lasers may have a 100% up-time). So let's assume 43%/12.9sec of fire, 30 sec of fire, and a 41sec total cycle time. Interestingly: that puts damage at 100% at 30 seconds. Add in recharge and it's 100%/41sec or 2.43%/secA pulse laser that never drains does 2.38%/secSo the beam is slightly better (more than slightly if the pulse does eventually drain the engine) in terms of raw DPS. It also will do better though most of each 40sec period (remember: the DPS is higher than 2.43 for the first 30sec, then drops till it hits 2.43 at 41sec, then rises again until 71sec where it begins to drop again. 2.43 is the lowest DPS the beam has. Of course, the pulse will eat less of the engine and so leave room for (more) shield capacitors, or a second energy weapon, which the beam will more severely limit.
I ran beam+Scatter, then dual pulse, and am now trying pulse+multi.