Tony,
I wasn't really talking about the search times coming back slow. My experience with CA/DA is that the searches are normally pretty efficient given the size. I think I was more worried about the SQL db's homing the vault stores getting unweildly. As ya noted, a lot of our enterprise customers get a veritable shiznit load (that's the scientific phrase) of mail. Even at 400b per message, it adds up, especially when you're talking about journaling.
I've seen medium sized companies do 10gb/day journal...and that was a slow day (a weekend even). The db for that vault store was a couple of gig in a week (which made for an unhappy dba). *shrug*
Although now that I ponder it (or ramble upon it, as the case may be), does it make sense to seperate the journal vault for security, ease of searching from CA/DA, or whatnot? Oh, well, I usually go with a seperate machine for CA and journaling anyhow, and I usually home the vault store for journalling local the box anyhow (so I guess the best practice arguement is kinda mute for me anyhow). I wish I could say it was for speed, but really I just didn't usually want to put that much I/O over the network.
The AVSMaxLoc key is new fer me tho, school me on what the recommended values should be for a rollover setting?