Since taking the rescue class, I've probably assisted with around 20 rescue classes at my LDS, with pretty much every instructor there. LDS policy is anyone taking the rescue class is welcome to come back and participate in future classes. Here are a few observations to maybe help you make some decisions of what is best for you:
Every instructor runs the class very differently, based on their background and experience. A former military special forces guy will run the class quite differently from a dive instructor who does IT as their day job, which is not to say one is better or worse than the other. But you will get two different perspectives, both which are fully compliant with PADI standards for the rescue class. One might focus more on physical skills, while the other places more emphasis on planning and analytic skills
No single rescue class will really make you particularly qualified to rescue anyone in most situations. For the most part, the class is like drinking from a fire hose because there is a lot of information and skills being thrown at you, which are overwhelming for most people (from personal experience and observations in several classes). The class gives you the foundations and some basic understanding in an environment more stressful than typical PADI certification classes.
The quality of the class instruction and skills is probably as dependent on fellow class members as the instructor. If everyone else in the class is an experienced, skilled diver, you will get a lot more out of the class than if fellow classmates are borderline hopeless. You're working as a team (or should be) on many of the rescue scenarios, although you can still learn how to delegate rescue steps based on capabilities of fellow class members. Working with both types over time is probably the best preparation for a real world rescue
All other things being equal, every class is different because conditions come in to play. A low viz day is very different from a high viz day for training, and current, surge, waves, temperature and everything else nature throws at you affects the class and what you get out of it. If the class is on a boat, lots more variables come into play as well
After you take the class, you will quickly forget most of the skills unless you perform them regularly. Unlike just about any other scuba certification class, the rescue class skills are the ones you hope you never need to use, so they are typically not something you spend time on when you go out diving for enjoyment.
The real benefit comes when you regularly come back and participate in future classes, either as a buddy, victim or helper. You are under no stress to perform (sometimes poor performance as an assistant for a rescue class is a plus!) and you get to observe everyone going through the skills for the first time. Think you did a decent job surfacing an unconscious diver when you first took the rescue class? Just wait until a student tries to surface you and you experience everything they do wrong. You'll quickly learn more than the first time through the rescue class to get another plastic card. You get to refresh your skills, practice in different environments, observe different teaching methods and approaches, and over time really pick up all the skills advertised for the course in the first place
If you're thinking of going on to become a DM or instructor, helping with a number of rescue classes makes it a lot easier to ace all the rescue skills needed for pro-level classes. One great rescue class from the best instructor hardly qualifies you for the skills you really need at the pro level
Definitely talk to the instructor before you sign up for the rescue class. If the chemistry isn't right or the guy really rubs you the wrong way, it's unlikely to get any better when you take the class
