I live just south of Wichita and own a 396T, HP-1, 436, and a 536. I also program a 996xt for one of the control centers at McConnell and used to own a 996t. I also have a ham license and run 5 radios for that (simulcast and error rate was on the test). Most of the post above are pure garbage--don't listen to them (except for ofd8001's explanation of simulcast which was remarkable and much appreciated). They may work for some people, but they have different systems than you do--they are not the same.
You and fp5930, like many others, are stressed about the $$ you spent and it's not working--been there. There is NO scanner on the market that works well with simulcast systems--explained by ofd8001. But you can expect fair to good. Judging by your location, you should be able to get good to very good, but don't expect perfect because it can't be done.
Simulcast and programming are your issues. DON'T change your settings--it will only make it worse. Go with the standard decode automatic settings (auto and 8). Like I said before, DITCH freescan--it's **** and doesn't program the radios correctly--use ARC PRO. Then watch the error rates--look up in the manual how to display that--lower is better and it should improve over time (don't turn the radio off, just turn down the volume).
My 436 and 536 sit next to each other--there is no rhyme or reason, but sometimes one will receive and the other won't--then vice versa. Sometime both won't work, sometimes both will. The HP-1 is worse--but what confuses me is that the Derby PIC channel comes in on my HP-1, but not the 436 or 536 (the only talk group that does that). I did dumb down the antenna on the 536 to a rubber ducky on a 90 degree adapter--seemed to help.
You have to program it correctly--all the frequencies have to be programmed (there are 20 of them), not just control channels since a P25 phase 1 system can and does change control frequencies to any and all, not just the ones that say control. Use WIDE FM--NFM makes it worse. Use the standard decode with automatic and 8--the radio will learn after some time and get a little better (thus the automatic). I've tried all the other settings and auto 8 is the best for now.
I got some news for you--Butler County is a simulcast system, the State system is simulcast too, and the Highway Patrol uses the Sedgwick County simulcast system--same one as Wichita PD. So it may be a programming issue.
I sent you a file for the 996XT for Sedgwick County--try it.
You can also take it to the Derby Radio Shack and they will program it for you for a few $$--or buy me lunch. In the mean time, double and triple check your programming. Lower the antenna (which is better for UHF anyway) and try different locations in the house (my living room works best, office not so much since it's closer to multiple towers). Try to place it where it will see only one tower (i.e., not next to a window, more house blocking the towers west and south of you.
They are still tweaking the system--even after 10 months, but it is fully operational and covers the entire county and most of the surrounding counties. My 396t is in my car and works fairly well--I hear plenty when I'm at Hartman Arena or the Pavilions.
PM me if you want me to program it for you using ARC--won't cost you anything and you said you work on the side so it's not to far out of your way. Will only take a few minutes and is not permanent.