I think it's time to eliminate the G1 and G2 lanes and follow the DL/AS/AA model with two lines, one for priority and one for general, and place the signs and straps near the actual boarding location. Having observed a few Delta boarding procedures lately, it seems to work better, at least in my experience, with few people piling up into different lanes, but rather standing away from the desk until they are called up.

Here is how I would reduce the people-clutter at the gate and speed up boarding by moving the fastest passengers on board first plus those who need some extra time or assistance.

1. Pre-board - wheelchairs and disabled, families with strollers/car seats - no stroller or car seat? Tough, you board with your group number
2. Global Services and First Class/Polaris through the "Premier Access" line (Premier Access Priority 1 on their boarding pass)
3. 1K, Platinum, Gold, Star Gold, through the Premier Access line (Premier Access Priority 2 on their boarding pass)
4. Premium Plus seated customers where applicable through the Premier Access line (Premier Access Priority 3 on their boarding pass)
5. Silver, Credit Cards with Priority Access, Paid UC members through the Premier Access line (Premier Access Priority 4 on their boarding pass)
6. General Boarding G1 - behind the wing - instructed to board along the general boarding line
7. General Boarding G2 - in front of the wing - instructed to board along the general boarding line
8. General Boarding G3 - Basic Economy - instructed to board along the general boarding line

Late arriving Premier Access customers can use the Premier Access line to cut in front of those in general boarding

Systems need to be reprogrammed to deny boarding to anyone outside the boarding number currently being called - customers without status will automatically receive the boarding priority of the highest ranking passengers on the same PNR