Personally, I'm still on the fence on this one. I like using DVI when my signal runs are short, and when I need to do long runs I go SDI. A lot of the time, I actually like what the SDI (or HD-SDI) signal looks like a little more than a DVI signal. If you are using a good scaler/converter like an imagepro, I think it actually can clean up the look of the signal (doesn't look as "digital") I have even done shows where I was taking SD content and in order to send to the truck we converted to 1080I, and it honestly looked really good, I was shocked, no pixelation or artifacting at all. Also, SDI and HD-SDI cabling is MUCH more robust, and the gear is much more available, so when you get a bad unit, finding a replacement is easy.
Fiber gets really expensive really quickly, and the cabling is not nearly as robust. Even the military grade stuff can get damaged quite easily given the right circumstances, and finding replacements are not very easy all the time.
I still think for long runs sdi or HD-sdi is the way to go, but if you can keep the signal runs short, then go DVI.
Oddly enough, the place where I see the most benefit of staying DVI, is when usign LOW resolution devices, specifically the element labs stuff.
First off, their processors for the most part REQUIRE 1024x768, 60Hz DVI signal, they simply wotn take anything else.
But, more importantly, if you are trying to do ANY pixel-accurate stuff on things such as versatubes, or versatiles, or even Stealth for that matter, you HAVE to stay DVI the whole way. I was doing a show where even the elemnt labs' box added a row of pixels to the bottom of the stealth, we by-passed it and went direct DVI from a catalyst to the processor of the stealth, and this went away.

just my .02

Jason