I have service in the Chicago area and I am very happy with the service. It is a night and day difference from where it was a year ago. Now I've had some in issues in other markets that are upgrading but out here my service has been much improved.
Sure, this link explains that those were changed from pcs 1900 to 800. http://s4gru.com/index.php?/blog/1/entry-131-updated-prl-builders-and-network-spelunkers-pay-heed-sprint-cdma1x-800-channels-and-sids-revealed/
According the 5 digit SID number you are showing, that is the 800Mhz SMR voice SID for Chicago. That would explain why you are getting a stronger voice signal.