Every time I've gone on a long weekend backpacking trip, I've used my above-the-ankle boots. My buddies and I normally pack for a bit of comfort, with 40 pound packs, each.
My problem: with uneven terrain, the stresses and strains that protect my ankle seem to slightly transfer to my knees. I own a couple of pairs of low hiking shoes that are made of the same type of tread, lug, waterproof-breathable membrane and leather as my boots. Just posing the question to the backpacking community: Who uses hiker lows on short backpacking trips? What weight is your pack when you use lows?
Your last question really nailed it for my determination on boot height - it depends on what weight I’m carrying. If I’m below 25lbs (usually ultra-light or short weekend) I’ll opt for lows. If I’m over 40lbs (usually several days of gear or in winter) I’ll wear full height. Somewhere in the middle I’ll wear whatever.
A second consideration I’d make is whether or not I’m prone to weak joints (aka sprained ankles). Fortunately, I am not and so I don’t give this much consideration, but I hike with others who are more concerned. Probably worth some thought.
Lastly, season/terrain matters and the more likley you are to be walking through sand or snow you’ll likely want the higher ankle unless you’re wearing gators.
Lately i have been wearing lows for all my trips, even with 35/40lb packs (taking the kids means being a mule). It does take a bit my care with where you step while hiking but the light weight keeps my feet happy and my legs moving.
I think it’s also worth considering the size of the person carrying the gear. I’m 6’3 wide-shouldered and even really fit I weigh 200 lbs. hiking in anything but high ankle boots is never in the cards for me. I roll my ankle at least 5 times in a full hiking day and with full boots I’m fine. If you’re tall you can try a lower cut but it might cost you some ankle problems.
Lows -- trail runners, actually -- for me for most of my backpacking and hiking trips. My load rarely exceeds 20 lb. and I find full-height hiking boots sort of clunky on my feet. If I were carrying a much heavier load or traversing really wicked, rocky terrain, I'd consider more ankle protection.
I would consider a low shoe for myself, but only on even terrain that's reasonably dry. With a full pack and uneven or slippery terrain, I'll wear my mid-height waterproof boots, laced tight at the ankles, for the protection and support.
I hiked in the backcountry at Capitol Reef NP where trails can be poorly defined, rocky, with cross-slopes and plenty of chances to roll ankles. I was carrying 35# and my ankles were fine.
My trekking poles were valuable in giving me extra support to improve my footing on the worst parts.
I use both and determine which by weather, terrain and activity. Admittedly I like donning my low cuts most of the time. I would advise you get good “trekking or hiking” specific shoes. Too often I see low cuts that are really around town walkers, and off trail they break down fast and loose support when wet.
I switch to my full height boots when the snow and muck are at there best, When I scrambling over unknown terrain, where banging my ankles is common, and when stability is effected by blind placement.
As noted by others weight of carry is a factor.