Many years back when at a campout with my son's Boy Scout Troop there was a parent visiting that was wearing some kind of water bladder backpack. She plopped down in a chair and then quickly sprang back up.
It turned out that she'd put ice in her bladder, and the bladder burst open when she sat down - flooding her back and rear end with ice water.
I've always been under the assumption that it was a cheap imitation and that the good brands would not have failed so violently (so to speak).
Or it could have been a Camelbak and ice got stuck on the lip when she screwed it on or maybe she didn't screw it on flush and the lid popped off when it became pressurized. I'll be honest my reservoir leaked last week when a piece of ice got stuck on my lid and it didn't screw on straight.
I do both. I use reservoirs for longer runs and for paramilitary events where I can not take off my pack to get a bottle. Every day I may have a half filled reservoir in my daypack but I also EDC a Nalgene Oasis (GI canteen version) with a canteen cup and Alice canteen pouch. Today I had both PLUS a 1L wide mouth Nalgene full of water and Chia seeds.
For public gatherings I tend to use a 1L Nalgene. Which I will also nest with a GSI cup for when I carry it normally.
I have never, ever, had a external freezing problem with my drink tube, down to below freezing. I do have a neoprene cover over the tube. I do have a dust cap on my reservoirs of which I own maybe a half dozen.
Camelbak is not the only option of course. Source is a great hydration company. Their design is made for soldiering abuse. it has anti-microbial properties. They have an ingenious cap that fits onto the mouthpiece area to recharge the bladder without having to take it off and open the lid. Platypus makes a reservoir very similar to Camelbak. They have a ziptop lid that is much larger than others already mentioned. And its never leaked on me from that closure system.
TL;DR- I use it all. 1L Nalgene wide mouths, reservoirs, Nalgene GI canteens. I have never had a reservoir freeze on me.