A couple of things I found issue with. Nothing huge, but a few logic issues
Always having a camera in the first room (we know that any place with surveillance these days have one in the lobby anyways) would keep a player on his toes as soon as he enters the mission.
Depending on where the mission entrance is, people don't always have the luxury of buffing outside. Even if they can, perk buffs (and some others) don't last through zoning so the players would instantly be at a disadvantage. I've always seen the two mobs in the hall area after the entrance as being a good way to still throw someone right in to it and can be a real test for pulling properly.
Something else I would love to see changed, is the removal of rollerrats (and the annoying lizards) within missions when you either unlock a door or chest.
Doors, totally agree. Chests, not so much. It's an established thing that rollerrats stow away in containers, so finding them in chests, along with lizards, makes total sense.
Another option is to keep the current refresh but no longer needing a garden key
Considering what a big part of SL the garden keys are, and the basics of how the SL beacon works, they shouldn't be taken out of the equation for the beacon. I do think the refresh time is too high, and that something nice to add to the beacon would be using it with no key equipped would transport you to Jobe.
Everything else looks good!