I've found that if the lines are fairly short, subtitles will work better than you think. They are incredibly bad if there's several lines of dialogue ... partly because many Americans read poorly and partly because it becomes distracting. Short and sweet works best.
Thanks for the reply.
I've consciously kept dialogue short and to the point. My concern is that several key plot points/twists are subtitled and could lose their impact because of this. I guess that if I keep the talking to a minimum I should be okay.
I did have a lengthy subtitled scene setting up a main twist but following a rewrite the whole scene is now dialogue free. (remember: show don't tell!

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