Hi Vic Nicholas and thanks for the query about the comfort compared to a harness system. I think a lot is down to what you personally feel comfortable using.
Traditionally with pads that are a set shape and can't be altered, if you have a simple strapping system which is also limited in where it can fix the biggest problem is not getting the grip where you need for them to stay in place, by having a malleable shell with velcro everywhere means you can get awesome grip to the body, and because the shape fits around you snug you don't experience the feeling of something fitting poorly and wobbling around.
The harness system is a great design and it really suits the type of pad which Aero make, my reason for just having straps is that this is all you need rather than the additional material / weight of the harness.
There are also two other options which are good, one is that you can wear Stretton Fox pads under a compression baselayer without any straps and they hold in place brilliantly. The thin and close fit means they barely appear more than 15mm off the leg. The other option is some players have requested shapes which allow them to place the guards into different harness or padman shorts pockets replacing the original inners, then with removable straps they can wear also without harness depending how they're playing.
I hope the above helps !
Cheers
George