I have had more fun on the trips I have not made with a dive shop group. First, it is more expensive. secondly, you have less freedom and flexibility, third, there are always a higher percentage of whiners in a "group" than what you find in the population that will figure it out on their own. You will not be alone, because there are people at the destinations and in general, it is very easy to make friends with people at those sorts of places. The few hundred dollar discount you get leading a tour is not worth listening to the lady complain every night at dinner about the mold in some corner of her room. Just my opinion....
I have done two trips to Palau as a " leader" (sort of) and two without. The two without were vacations and a blast. The other two were two weeks of being around 20% people I would never choose to spend five minutes with. Unlike real life, you can't make a polite excuse and duck them. The majority of the people were fantastic, but you always get those few that are just not who you want to vacation with. I felt a little like one of those farm dogs they tie the dead chicken around his neck to try and convince him to not to kill the hens.
Like the previous poster said, if you put together a group of your own friends and call the destination operator...you can usually get a deal.
Of course, then there are the people who would not want to be stuck with me....I don't do live-aboards out of my empathy for those people. Two-three days, I think I can be okay. A week? on a boat? I know better than subject anyone to that.
Don't do a group tour for a discount, only do it because you want to be WITH the people going. (how can you ever know that, signing up anything but last?)
By buddies say I am sounding jaded.....sorry just spent a day with some loud profanity and keep imagining having her on my trip.