Yes, the agency can be important IF:
You can NOT start CCR or SM in gue, and that is the bigbig problem. When I started diving I was already interested in sidemount and ccr. That was not possible within gue then, completely not. So for me it was not the agency to start technical diving. The fundamentals has the big problem that it is required and in any other agency it is optional. If an evaluation was possible I had maybe done normoxic and then T2. Just to know from different agencies (I have taken courses from different agencies, different instructors, sometimes absolutely NON-DIR where I dove DIR, sometimes absolutely DIR-style. This gave me a big and broad vision about technical diving and how people do it. Money is not unlimited and if you want to do 100m dives, you need a full tx cert after you normoxic card, whatever agency and not a fundies pass. You can do an evaluation, no problem, but no, not courses again. I dive with all kind of divers. And no, the differences are not that big. Of course you have old fashioned seashorses in the water with bad finningtechniques, but overal it is not that bad as sometimes stated here. But I have also seen gue tech rated divers that didn't has practised and their skills can be lower than from another diver that practised.
We were refused for a 50m dive for project baseline as we dove ccr and oc in a mixed team, that was impossible then. But then people move to ccr and other agencies, and gue start ccr, after T2. But that is also changed to after t1 now. Sidemount is now also possible, but still not as basic course.
Remember the time, deco by head, ration deco. I learned in early days pragmatic deco. And now, wow, even gue uses a decoplanner, pragmatising the stops and hey, that is what I learned already before they adopted it. But I use it also for best mix instead of standardgases. Standardgases are nice, but sometimes a best mix is a better choice. I teach the advanced nitrox course. 42m on air. I would never use helium myself already at 30.2m, that is in my eyes a waste of that expensive rare gas. But if you want to do, no problem. It is a freedom divers have. My personal limit on air depends on darkness, cold, etc. But I don't teach the technical diver, I have to dive on air also then and am responsible. Then I will say do normoxic trimix.
Remember all divers are human. The level of the diver depends partly on the instructor, but maybe more after THEIR WILLING to practise AFTER a course. As soon as you think you are already on the level, your level goes down. This happens with divers from every agency. Divers who know their theoryknowledge is bad and they learn this slow, they need to practise this after a course again.
I do a lot of things 'DIR/GUE-ish'. But yes, I also can take ccr, sidemount, sm-ccr. Also I took a month ago a normal bcd, wow, I like that freedom. If people learn to dive with me, they get a normal bcd, but I use a longhose. And explain them why. If people decide to buy a normal regulator set with octopus, no problem, I will also teach you then. I also dive solo, very important for me on some dives.
As there is no proof that agency X has more accidents than agency Y, there is no proof that 1 agency is better than another. It is just a personal opinion. Evaluation in diving is seen in every agency. And every agency has possitive points and negative points. If the negative points are limiting for you or so big you cannot agree, choose for another. You have the freedom.
Yes, sometimes there are bad instructors, but what I said the best instructor is a bad choice if personalities don't fit.
So to start with a next course: search for an instructor that is allowed to teach the course you want and decided if the personality fits. Then look if his/her teachingqualities are on your norm. And norm can be different from diver to diver. If you think RAID is the way to go, why not?
I only would say if you choose it and want to use in Europe, you must know that raid is almost unknown here and maybe you get problems that the card is not accepted. I point I would figure out if you want to use it here.