Whenever I play soldier/engineer/vanguard on higher difficulties I move around freely all the time, heck I was moving around freely with a level 8 batarian soldier on silver, with the krogans it's even worse since I can just run around and punch people in the face till like wave 6...soo dunno about this hugging walls 24/7 crap.

And human sentinel has another build: 6/5/3 or 6/3/5; just use powers with this build until you feel like you actually need the tech armour.