Actually, I've gotten along fine in wet weather with a single-wall tent, although I might want to switch if I were regularly backpacking in prolonged rain. Our prolonged rains usually start in November, and by that time, the days are too short for backpacking anyway, since I don't want to be cooped up for long hours of darkness.

Since, until the last few years, I've had to accomodate a 75-lb. dog, my tents are 2 person anyway.
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May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view--E. Abbey