Actually, save for very specific circumstances (for example, kiting Swarm Queens), you want to get as close as possible with energy weapons. Set your PD weapons to Final Defensive Fire; the missile speed issue only comes up if you're trying to use them as interdiction weapons (which you shouldn't be doing anyways if you're being sensible and using Gauss turrets as PD). Yes, mesons perform well at extreme ranges, but the thing is that outside of the tiny range interval where railguns of a given TL can't reach and lasers are at their minimum damage, they're lackluster against anything without thick armor or good shields. At "closer" ranges any other E/K weapon is going to deliver much higher damage output, and more importantly, will put enemy ships out of commission much more quickly, which in the long term will substantially reduce your repair/replacement costs.
On another point, you actually want a mix of lasers and mesons when dealing with Invaders; mesons to pierce their shields, and lasers because those are the most effective PD weapon against their plasma torpedoes.
I just tested the Point Defense against Missiles again, and even with Final Defensive Fire (which I use anyway), missiles less than 5 seconds away hit without being shot at.
Afaik this is due the detection cycle being after the movement cycle, which means that the missiles (which are shot after the last detection cycle) move and hit before they are being detected, which is a prerequisite for pointdefense working.
I would also disagree on low-range engagements being preferable, because if the enemy has stuff that goes through your pointdefense you're dead before you reach them anyway, and if you can stop all his missiles, staying at a range at which he can't engage (or does so little damage that your shields can catch it) while doing permanent damage (thus mesons) yourself results in taking pretty much no damage at all.
Wait, not even CIWS can hit something that can cross it's range in five seconds? I thought that's what final defensive fire and CIWS was supposed to deal with.
Ah, I see what he's getting at. He's flying his ships so close to the enemy missile platform that the missiles can launch and hit in the same 5-second tick. Which is, uh,
very easy to avoid. You'll already know the speed of their missiles from taking fire during your initial approach, just set your follow order to be [(missile velocity)*5+n], where n is whatever safe margin you want. Given that (especially with the new drive model) missiles are rarely going to be faster than ~20,000km/s (and markedly less than that for most things), they only fire once every so often (which means that you can predict their firing patterns and close in while they're reloading, then back off to a safe range when they fire), it's not particularly difficult to deal with. That aside, you're using E/KW offensively, so your beam ships are going to have thick armor -- take a few hits, unload your laser of doom, wait for it to recharge its capacitors while your enemy enjoys being a floating pile of scrap. Or, again, play smart instead of hovering inside their insta-hit envelope when they're nearly reloaded.
Of course the real note that this is dancing around is the fact that
all E/KW pale in comparison to missiles (except perhaps for anti-missile work) primarily because of the vast gulf between their effective maximum ranges.