My training was to get the victim and myself vertical, using my left hand to hold up their inflator, to dump gas during the ascent (possibly switching to my own, as well, as needed), and right hand reaching around to hold the reg in their mouth.
So how do you avoid dropping them or being left behind if one hand is on the inflator and one on their regulator?
TBH this all sounds like rationalising post purchase.
I dive in the UK and most of my rescue stuff happens in Uk quarries and a large part was with Suuntos. The least of my troubles was knowing the depth.