I remember teaching this section of Acts one summer to a second year Greek class. I brought up the double meaning and noted that F.F. Bruce, in his Commentary on the Greek Text of Acts, came down on the side of "too superstitious." I, in turn, made the argument for "very religious." One doesn't argue with Bruce lightly!
A bit later in the class we were reading Theophrastus's Superstitious Man (English text here). The students, of course, didn't remember the word at all. But it drove home to me the double meaning of the word. I've wondered about how to take it for years (this was 1985), even though I still came down on the side of "very religious." I think Rowe has pegged it right... If I ever teach that section of Acts again, I'll point out his interpretation. Very satisfying.