Definitely. IME, once the purge difficulty is set to 5 or 6, all of the purges rated with a difficulty of 1-4 stop spawning. Apparently, this is not intended behavior, but in practice it seems to be how it shakes out.
For example, if difficulty is set to 6, a base in the immediate vicinity of Sepermeru would only suffer attacks from Scorpions or Locusts since the Relic Hunter purges are all 1-4 difficulty.
On my PC server host, I can open the server’s console output and look for messages starting with “ConanSandbox: Purge” and see what the server is intending to purge a clan with. If it’s undesirable, I have time to cancel it and try another using console commands, but it doesn’t sound like those will work on a console server unfortunately.
For purges with lots of crafters, I’d recommend building at the same latitude as New Asagarth. When I was on an Official, I had excellent luck (and variety) in the center of F10 (i.e. in the same valley as NA, not atop the cliffs). After that, I moved to NE A9, where I got nothing but Cimmerian Beast-Tamers and Berserkers, both of which yield tons of thralls.
BTW, if you have the ability to edit the ServerSettings.ini for your server, one helpful change to make is this:
When you do that and then look at a building with a Repair Hammer, you’ll see an extra line at the bottom that shows the Building Score. The higher that number is relative to your clan’s other buildings the better it’s chance of being the purge’s target. Note though, that each building that’s on its own decay network will have its own separate score. Additionally, if a building’s score is too low, the purge will never select it. I believe the minimum score is around 800-something down south, and 2000 or so up north.