I can't speak for the providers but here's my two cents.
Chicago is not as out in the open as the Southern cities for this business. The previous Daley mayoral administration did a lot to kill any outward signs that it even existed and that legacy continues to this day. Its created a culture that lacks the benefits of competition that places like Dallas experience which make it a better place to hobby.
For instance, MP and strip clubs are all generally above board and a waste of time.
ECCIE is a popular board in the south the same was ASPD was but its not really centered around this part of the country so that explains the lower number of registered users from the area. From my perspective its a good resource for seeing what legitimate providers from your area are coming through town.
BP here while heavily trafficked is usually full of sub par providers if not flat out rip off artists. For seasoned hobbyists here its apparent that out of those hundereds of ads there are probably only 10 worth following up on. Its made it necessary to sort through a lot of chaff to find someone worth seeing on those boards. RS2k thankfully fills that gap but it also is a higher tier of financial commitments for people who choose to use it.
Its still an active city for this sort of thing but people here are far more discreet and less inclined to openly discuss activities because drawing too much attention to it may bring the ire of LE. If I were a visiting provider I would stay away from Dupage or Mchenry counties because of over zealous LE with nothing better to do especially if you advertise on BP like sites. If you are going to advertise on ECC i would recommend doing so at the very least a week in advance of your visit here so people like me who specifically want to see southern girls have time to catch the ads and do some vetting so we can see what you're about since you'd be new to the area
What I've noticed in the past six months with regard to Chicago (my favorite city in the world right now) ... is that a LOT of ladies have "discovered" it as of late. And it's going to become a glutted market soon.
Like Texas is, now.
Good luck with your travels there. I love the place.