first off, i hike very uneven terrain with, for the most part, very rocky trails (70+ years old trails with a lot of erosion from rain runoff exposing rocks) - near constant gaining and losing elevation. while the overall elevation in connecticut is nothing buy a small "bump" to you who hike the rockies, the trails i typically hike have a cumulative elevation increase of ~1,200' to 2,500' per mile traveled (max elev above sea level is only ~750'. ok...ok...you can stop laughing now!!!). i really don't know how the *BEEP*. elev. change compares with the rockies, so i'm not trying to impress anyone (obviously the 750' impresses no one!!). it's just that the post i'm replying to mentioned ascents and descents, so i'm tyring to give some idea of how the GG poles are being used.
now, as to your question re: length adj.
no..., i don't miss not being able to adj. the len.
i do use my poles for ascents. even though the GG pole shafts have a small diameter, i just i grab them down lower and my hands, bare or gloved don't slip (prob. need some leather on the palms - haven't tried with just wool palms), . i suspect wool palms might slip on the pole shafts. i'll have to try this soon before the weather gets too warm here.
poles are used for descents, of course. then, i place my palms on the tops of the grips. yes..., this can cause me to be leaning a bit forward on very steep descents, so extra care is req'd - especially with some pole flex in the GG poles. i may purchase another pair of GG poles this year which are 5-10cm longer than the "proper" length for my height. the thought is that this would make descents easier. if it turns out i'm wrong, then i can remove the grips and cut the extra 5-10cm off of the poles & reinstall the grips. having my hands slightly above optimal/proper level when traversing flatter portions of the trails may not be much of a problem (a little extra cardio workout, i suspect, having the hands above heart level due to the longer poles), but i don't know yet. anyone else try this approach, i.e. longer poles, already?
not having to periodically check the length (by comparing the two poles side-by-side), or tightening them "just-in-case" is an advantage of single length shafts. i no longer worry about the poles collapsing from the collars loosening up. once i got used to the flex, i no longer worry about the poles breaking. however, i do take extra care not to jam the tips into small cracks and have learned to "feel" when this occurs and not "lever" the lower pole shaft against the rock, but instead pull it straight out of the crack. i said "feel" because i usually do NOT look down when trekking on rocky, uneven trails unless it is one of the very steep portions where a fall can mean more than a bad bruise.
right now, i just use an Integral Designs eVent Unishelter bivy and not a tarp for sleeping. so, not being able to adj. the length of my poles is no problem when it comes to shelter. however the GG website shows their SpinnShelter tarptent pitched with longer poles, so you may not have a problem using non-adj. poles with some types of tarps.
hope this info helps.