I wonder how much they take out if you're lvl 50 anyway as long as there isn't a ghost town after i'm happy.
I've had Dragon Bridge, Karthwasten, Rorikstead
and most of the Orcish Strongholds absolutely decimated. And I've only played about 20-25 hours since I've installed Dawnguard. I never even entered any of these, either. I was just close enough to have the cells active. Hell. Could be more, I don't know. I've only discovered these casualties after reading the horror stories in this thread and the tens of other similar ones.. and going to check if I was equally screwed. I'm at 58 (Almost 59) at the moment.
At least I
know when there's a dragon nearby. I can go and defend the idiotic civilians and reload if any of them die due to fist-fighting a damned mythical beast that can breath fire and swallow you whole. (Though I have to admit - it's pretty badass. =P)
I honestly don't know what can be done to regulate the issue without removing it entirely, or having it scripted so that they spawn
very close to you after fast-travelling (Just out of visible range?). This might break immersion for PC players when the content is released on their end, due to the amazing draw distances they can muster.. but they can mod the entire issue out if they so choose - and they get mods in
general. So I don't care what they have to say. =P
The not knowing is driving me insane with paranoia. It's gotten to the point where I dread even loading Skyrim up. As I said before, the same thing happened after Lonesome Road with New Vegas. Those damned Legionary Assassins started spawning once a day - Way, way out of visual distance. They were cleaning the clocks of anything inbetween me and ol' Boone.
And they matched me level-wise, and damned near equipment wise. I was the only thing that could possibly take them down short of a Deathclaw pack.. and even then I'm not sure. Hah.
This is much the same with the Vampire Death Squads. I'm only out-leveling guards by 8 levels. Apparently 8 is enough to completely clean the floor with 'em. Because I watched a Master Vampire, Mistwalker, and two Thralls take on six guards in Solitude and come out on top. Shameful.
Hopefully we get a resolution to this soon. A healthy case of paranoia - as with dragon attacks - is good, and all.. But I'm damned glad I already did the miscellanious quests associated with those that were wiped out. Sure as hell won't be making a new character until this gets dealt with.

Edit - - - Just thought I'd add that all of this I experienced was during the daytime hours, and after completing the main quest on the side of the Dawnguard.. Have to give the Vampire goonies points for bravery, eh?