Actually, paralyzing has limited time too 
I mean, except different kinds of damage and few strange stuff like virus and virophage, here is many funny ways to neutralyze aliens: paralyze, electroshock, sonic, impact, even mind control. But only one of them is really useful :} I prefer to have technology like ‘aircraft paralyzing box’, or a lot of ropes 
Yes but once it’s paralyzed you can apply a few more doses to keep her calm for a dozen turns
Best ways to neutralize aliens IMHO are grenades and aimed shots to rip away their arms if you mean not killing them i’m not a great expert: crabs and tritons are easy, syrens i panic them then close in with a couple guys and smam neuralyzer.
Worms and Facehugger a shot is enough, the problem is having them alive in range and not surrounded by returning fire crabs. Maybe finish a nest leaving a sentinel alive and hatch an egg at a time until i can capture a live speciment
Chirons never captured one, wondering how to fit one alive in the Manticore without leaving some soldiers out, Sentinels neither, but i dont think it makes sense to capture one.
so far i only havent vivisected a chiron and a fire worm…but what you say is mostly correct…leave those you want to capture for last…so far it’s the best way to get what you want.
which means that when you’re inside a nest…find the spawnery and hit it hard until it’s 1 shot away from death…then paralyze what you want, and finish the mission…worked for me 
Keeping the fireworm or mortar Chiron last, easier said than done Goo Chirons maybe
u rip their abdomen off without killing them…that disables the mortars…only problem being that they flee afterwards, so…