There is no way you can ensure you never hurt someone. It sounds to me like your fear on this topic might make you useless as a therapist - or worse, bring about the very thing which you fear - inadvertently hurting somebody.

As for the idea about focusing on research rather than client care... It sounds like you have very strong opinions on right/wrong modalities. I'm not saying having an opinion is wrong (I also don't care for CBT), but to be a good researcher you have to be more objective than it sounds like you might be able to be on this topic. I could be wrong. I'm just going off of your enthusiasm for EMDR and hatred of CBT. How would it make you feel if you had to work on CBT studies, as they are more common than any other type, in grad school or when you are a junior researcher (or whatever you would call it)? It's not like there are constantly a ton of studies going on of other modalities, unfortunately - so you would be lucky if you managed to get in on a team studying one of your areas of interest. Do you think your dislike of CBT would influence your work? And the same question for EMDR or one of the other areas you expressed a positive interest or experience with - do you think those could unduly influence you if you worked in a research capacity? Would you be willing to relocate to live wherever the studies take place? I have looked into participating in studies (as a client) before, but there were never any near me - and I don't live in the middle of nowhere.

Anyway, just a few things to think about. I wouldn't become a therapist if you think you'll be constantly questioning and doubting yourself. That would be miserable for you and also make you pretty ineffective probably. If you want to pursue research, just make sure your passion is harnessed appropriately and doesn't impair your ability to think objectively.

I am currently a student (not in this or a related field) and I honestly can't wait to escape. Not sure anything could possess me to return to this life of penury if I had escaped it. I preferred working a 40-50 hr workweek much better. But that's me.

ETA: Also, I think that while doing research sounds exciting, it might not actually feel like it if you were involved. Actually, I am talking about myself here, because I think it would be extremely boring. Research involves so many stages and is such a long, drawn out, laborious process that I feel like pulling my hair out just thinking about it. Months or years. Then more months and months analyzing the data and months and months writing a report of the findings and submitting them for publication. Ugh. Academia is not for me.