First off, diving off of Largo is about as low stress, high fun diving that can be done. Most of the reefs are no deeper than 40' (depending upon where they drop you and the dive plan) which makes for zero safety stops, easy ascents to spot the boat, and other than buoyancy (which is more difficult shallow) the dives are pure enjoyment.
There are many options for boats. Brent and Blue Water divers runs a FIRST class outfit. If you are AOW, he is NOT going to charge you extra to dive the deeper wrecks... However, if you are NOT comfortable diving them, IMO pay the extra to get someone to accompany you.
The time to decide you needed an instructor is NOT when you are at 100'fsw on the Grove, and panicing because you are uncomfortable.
Brent LOVES to dive the Grove. I booked on a Monday/Tues, and as I was single, he was my dive buddy. He was an excellant dive buddy, and made my Grove Dive MUCH less stressful for which I thank him. On dive two, as he was able to keep up with my air comsumption
we booked a solid hour on the Benwood. As an instructor he is not always available to dive, but with as much time as he has spent diving the Keys, it's obvious he still loves it, and IMO was the best DM I had over 18 dives in FL when I was last there.
IMO, when diving deep wrecks, do NOT jump on a cattle boat with an AOW cert, little confidence, and a ton of divers that may or may not belong on a deep wreck in current. However, booking a crowded boat for shallow reefs is not all bad if the price is right assuming you can partner with someone who can get 1 hour out of a tank of air (assuming you can).
IMO talk with Brent, and Blue Water Divers. He's a good guy, a smallish OP, and will do you right even if he's about $15 more a day then the cattle boat Ops (IMO worth it.. totally).