I've skimmed through these forums and I've noticed that in several threads people have been discussing which of the aformentioned duals is better. This post is kinda going to be useless but I thought about it a little bit (had no choice, my life is really boring), and I decided to post this for the fun of it.
This is a formulated comparison between the two in several categories using maths:
First of all, when it comes to normal attacks, Dual Ether wins since it has a higher firing rate, hence the greater DPS. Even though these two are mostly compared in their ability to charge, I'm giving Ether a point because it still counts towards it's objective value. Ether 1:0 Heat
When it comes to charging, charge damage is pretty much an empty number. DPS is what we're looking for. Ether, with a HPS (or fire rate) value of 1.23 (max Reflex Coil) and 250 damage per hit (max Killing Blow) has a DPS value of 308. Dual Heat, with HPS=1.09, and 375 charge damage, has a DPS value of 409. Dual Heat wins by higher DPS, but it should be noted that Ether, due to it's higher fire rate, is much better at dispatching swarms of enemies with Intake Capacity (health + shield + damage reduced by armour) of 600 or less, which is most enemies, by one- or two-shotting them. Due to this, I'm awarding each of these a point. Ether 2:1 Heat
Multi-targetting. Heat only hits 3 targets, while Ether can hit more. It seems like a point for Ether, but if you're ever swarmed so hard that 4 or more enemies are within your range, you're probably already getting raped too hard for it to work. Point for each since it's basically the same thing. Ether 3:2 Heat
Ether has a high bonus on sliding attacks and wall attacks. Also, it constantly staggers enemies and has triple damage to infested. Heat has fire. Point for Ether in the Special Conditions category. Ether 4:2 Heat
If used as a charge weapon by Ash or Loki in conjunction with their Smoke Bomb/Invisibility which gives a constant crit on every strike pretty much, they're nearly equal since Ether's crit DPS is 616, and Heat's is 614. Both gain a point. Ether 5:3 Heat
Personally, I think Ether is better because of the aformentioned reasons. If anyone has something to add, I'm willing to tweek my calculations. It's possible I'm wrong so please contribute. :D