I think it would be a mistake to look at that CG inspection sticker as gospel that a vessel is safe. The inspection is a snapshot in time. The inspector comes on once per year and checks that the vessel is in compliance with written regulations in effect at that time. They come back the following year. A well run 6 pack is beholden to the insurance company to maintain the vessel at a certain level of compliance ALL the time. You have to schedule a CG inspection, the insurance surveyor can show up any time.
I think you'd be much better off to become a savvy diver. Prior to booking a trip, ask how many issues of license the captain has. We're proud that we're Captains on our (2nd, 3rd, 4th, whatever) issue. if it's the captain's first issue, maybe he isn't that experienced. Ask for the latest air test. If it's over 6 months old or the shop doesn't want to provide it, keep walking. Does the compressor have a CO monitor? If the answer is no, keep walking. If the shop can't afford $450 for a CO Clear, they aren't really in business. Ask for their limits of liability for Hull, P&I, and in-water liability. Hull is like collision on a car. P&I (Protection and Indemnity) is like Liability. The biggie, in-water liability, is where you are protected from the boat doing something stupid like leaving you behind. It's what covers the divers when they are not on the boat. For an insurer to grant a in-water policy, the operator must have their crap together and meet certain insurance company requirements. They check that the operator does these things. Look at the boat. Hey, we all have chipped paint at the end of the season, but is the fiberglass damaged? Are the rub rails shattered? When you see the engine hatch up, is there a smoking pile of rust in the bilge? Are the life jackets where you can readily get to them? Are they stowed or used as pillows? Have folks been stubbing out their smokes on the life ring? Is the dock safe or does the crew say "watch your step"? (I'm guilty of that one) Does the boat/Captain/DM give you a good competent feeling when you step on, or do you kind of look around sideways when you look in the cockpit with a queasy feeling?
Quiescence Diving built their reputation and a 35 year business in the keys running 6-pack boats. I'd compare any of their boats with any inspected vessel anywhere in the keys. I'm sure there are other reputable 6 pack operators, as well as there being very scary inspected vessels too. Remember, most keys boats are dual certified, meaning that if there aren't 7 payers on the boat, it can be operated as a 6 pack too.