I've used all kinds of tapes and rarely had dropouts. The only real issue is the Z1 if you're shooting HDV, because dropouts on there can be bad news (potentially you lose half a second of footage, whereas on DV you get a single-frame video glitch or lose one frame of audio).

However, I just shot an hour of Z1 footage on a cheap Panasonic tape and had no problems.

Tape is such a minor expense, comparatively, that an extra couple of bucks (pounds) for good tape seems like a good idea.

I hear that the cheaper tapes are great. I've never used them. Just isn't worth the gamble for me.

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The aim of an argument or discussion should not be victory, but progress.
Joseph Joubert, essayist (1754-1824)