If it's fantastically important that you don't get drop outs, then shoot DVCam. DV Tapes are fine for this. There is a theoretical reliability improvement, BUT ...

... in practice, I'd rather have the extra 20 minutes of DV given that I've never had a noticeable dropout with DV, and the digital picture is identical to DVCam, so once it's captured the tape system is irrelevant.

I'd have to disagree with that, I'm yet to see a DV tape without a dropout. You've got to be pretty vigilant to find them of course, they're only a few pixels in one frame, hardly likely to ruin anything but they can get worse if you're encoding to mpeg-2.
In general though there's no real advantage in running the camera in DVCAM rather than DV, ignoring dropouts there is zero difference in image quality. DVCAM does add locked audio, yet to see where that makes any difference unless you're doing a linear edit, in which case you're unlikely to be here. The other thing that DVCAM on the 170 gives you is control over TC, again a bit of a yawn really.
Still if I'm shooting only short segments I'll switch to DVCAM, tape is so cheap it isn't a factor.
For master copies though I always record to the D5 shell tapes in DVCAM.
As to those MiniDV sized DVCAM tapes, save your money, unless you like the bigger box, I guess you get more room for the label.
Bob.

I'd have to disagree with that, I'm yet to see a DV tape without a dropout.

Bob, I'd have to disagree with that. For what's worth, I've been shooting for over five years and I've never had a dropout in all that time. I attribute this to the use of Sony's DVCAM tape and their newer Digital Master tape, both in the mini-DV size. I'm willing to spend more than most as an insurance policy against dropout, so to speak. So far, it's paid off in spades!

Jay,
they're VERY hard to find and really only of technical interest but go through a tape frame by frame, you'll almost certainly find one tiny sparkle. They seem to affect the audio more so than the vision, just a tiny 'zzut'.
I don't have the figures for Sony's SD stock but on their HDV stock their own performance data shows no improvement between their 'SD' MinDV $6 tapes over their $35 HDV master tapes for less than around 10 passes. We've had a lot of clients shoot a lot of HDV on the $6 tapes and so far no ones mentioned a problem with a dropout, factor in though that HDV has better error recovery than DV.
Also one other small factor, your chances of seeing a dropout in DV depends on what and how you shoot!
That last bit I'd seen so many times but never understood why. Turns out that depending on the complexity of the frame the image stream can contrain a large amount of padding.

Bob.

Bob, rather than sitting down and doing through tens of millions--perhaps hundreds of millions--of frames, why don't I just take you at your word!?

Jay,
PLEASE neither credit nor blame me for this. I think it was an article by Adam Wilt that started me on this. I'd lived in ignorant bliss until I read it and now my life has taken yet another nasty turn for the worse. May the fleas of a thousand camels take up residence in the man's armpits!
So if you can find a way please erase all knowledge of this, and do so; urgently, trust me once you start seeing them, that's all you see, content be damned.
Bob.