Yea, the thruster pack is a bit less noticable/low profile (unless it's in use), and I would say it somewhat resembles a boomerang in overall shape. The AA modules are much less conspicuous than they were in Reach, with the exception of the jet pack, but they are all noticable if you have a sharp eye. What makes them the most difficult to spot is that you pretty much have to try and catch a glimpse on the fly unless you pore through matchmaking clips. Yet another time when giving us forge mode support in theatre would have been great, as we could simply line up all the available AAs on one map and just snap a screen shot, swap to the next AA, and repeat. I've only been able to really note the differences during slow-paced custom games and Spartan Ops playthroughs.