Totally agree about sealing the vents properly—makes a huge difference. I actually found that using reflective insulation film (the kind you can get at any hardware store) around the window kit really cut down on heat transfer. Just trimmed it to size, stuck it on with some double-sided tape, and it worked wonders.
Also, one thing about portable units is placement matters more than you'd think. I had mine tucked into a corner at first, but noticed airflow wasn't great and the unit seemed to struggle. After moving it out a bit, giving it more breathing room and making sure nothing blocked the intake vents, performance improved noticeably.
As for noise, you're right—some models are quieter than others. But if anyone's sensitive to sound at night, placing a small bookshelf or even a decorative screen between your sleeping area and the unit can help diffuse noise surprisingly well. It's not perfect, but every little bit helps when you're trying to sleep...
