BE24 PLT HAS NMAC IN DCA ADIZ BELOW CLASS B AIRSPACE.

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I WAS FLYING TO JYO TO DROP PAX AND THEN FLY TO ZZZ. I FILED AN ADIZ FLT PLAN; ENTERED AT GOLDA AND WAS ADVISED TO STAY BELOW CLASS B AIRSPACE. COMPRESSED INTO THE AIRSPACE BELOW 1500 FT AND WANTING TO STAY AS HIGH AS POSSIBLE TO AVOID THE TWRS THAT ARE LITTERED IN THAT CORRIDOR AND STAY WELL AWAY FROM THE FRZ; I WAS CRUISING ALONG AT ABOUT 1400 FT WHEN ADVISED THAT I WAS IN THE CLASS B. I DSNDED TO 1300 FT AND THAT SEEMED TO TAKE CARE OF IT. THE CTLR RPTED THAT MY ALT WAS WITHIN ALLOWABLE ERROR. I WAS APCHING TIPTON FROM THE E AT 1300 FT WHEN A CESSNA TOOK OFF FROM RWY 28. I MAINTAINED A PARALLEL COURSE TO THE RWY SO AS TO NOT INTERSECT HIS PATH AND MY CRUISE AIRSPD COMBINED WITH HIS CLBOUT AIRSPD INDICATED THAT I WOULD PASS HIM REASONABLY FAR OFF HIS L WING AND THAT I WOULD OVERTAKE HIM QUICKLY. TIPTON IS ONLY 150 FT IN ELEVATION; SO HE SHOULD HAVE BEEN NEARLY 200 FT BELOW ME AT BEST IF HE WAS STAYING IN THE PATTERN. PAST THE DEP END; THE CESSNA TURNED TOWARD; CONTINUED TO CLB AND PASSED PRETTY CLOSE BEHIND MY AIRPLANE. THE GAP CLOSED VERY FAST. AFTER THE CESSNA PASSED BEHIND; THE CTLR TRIED CALLING ME TO GIVE ME AN ALERT; BUT; WHEN HE SAW THAT THE CESSNA WAS NO LONGER A FACTOR; WENT ON TO SOME OTHER AIRPLANE WITHOUT COMPLETING THE XMISSION. I CALLED HIM BACK LATER WHEN HE DIDN'T SEEM SO BUSY AND HE LET ME KNOW HE WAS ABOUT TO TELL ME ABOUT THE PLANE I HAD SEEN. NEARLY THE SAME THING HAPPENED SHORTLY AFTERWARD OVER GAITHERSBURG WITH A PLANE WORKING THE PATTERN THERE. THE DIFFERENCE THERE BEING THAT I COULD HAVE CLBED IN THAT AIRSPACE...ONLY TO HAVE TO COME BACK DOWN A FEW MINS LATER TO APCH JYO. CONTRIBUTING FACTORS: 1) COMPRESSED AIRSPACE. THE LATERAL DISTANCE BTWN THE CLASS B SURFACE AREA AND THE FRZ ISN'T VERY FAR. TIPTON IS IN THE MIDDLE OF IT. THE VERT DIMENSIONS OF THE AIRSPACE ARE POOR AS WELL. A 1500 FT CEILING AMIDST TWRS PUTS TRANSITING TFC RIGHT AT PATTERN ALT. 2) POOR ATC STRUCTURE AND OVERLOAD. THE CTLR CTLING MY AIRPLANE WAS OBVIOUSLY NOT WORKING APCHS AND DEPS. IT APPEARED THAT HE WAS ONLY WORKING ADIZ TFC. HE WAS NOT CLRING ANYONE INTO CLASS B AIRSPACE TO MAKE EFFICIENT USE OF IT AND AVOID CONFLICT. IT APPEARED TO ME THAT THE FREQ AND CTLR WERE DEDICATED TO ADIZ TFC AND HE WOULD HAVE TO HAND ME OFF TO ANOTHER CTLR IN THE CLASS B. GIVEN HIS WORKLOAD; IT APPEARED THAT HE WOULD NOT HAVE BEEN ABLE TO DO THIS. IT ALSO APPEARS THAT THE SYS IS DESIGNED TO REDUCE WORKLOAD ON APCH/DEP CTLRS AND NOT TO MAKE EFFICIENT USE OF THE AIRSPACE. 3) COM. IF THE CESSNA ENTERED THE AIRSPACE LEGALLY; HE WOULD HAVE HAD TO TALK TO CLRNC DELIVERY TO RECEIVE HIS SQUAWK. IF CLRNC DELIVERY LOOKED AT THE RADAR OR TALKED TO THE CTLR WORKING ME; THE POTENTIAL FOR CONFLICT WOULD HAVE BEEN SEEN AND A HOLD FOR RELEASE INSTRUCTION COULD HAVE BEEN ISSUED TO THE CESSNA. THAT DIDN'T APPEAR TO HAVE HAPPENED. 4) FREQ CONGESTION. I SAW THIS SITUATION DEVELOPING WHILE THE CESSNA WAS STILL ON THE GND. I COULDN'T ADVISE THAT I WAS TURNING TOWARD THE FRZ TO AVOID THE TFC; OR ADVISE THAT I NEEDED A CLB TEMPORARILY TO AVOID THE TFC. FUTURE CONSIDERATIONS: 1) I AM AN IFR PLT. I WILL NOT FLY VFR UNDER THE CLASS B RING AS I DON'T BELIEVE IT IS SAFE OR WELL CTLED. THE STRUCTURE OF THE AIRSPACE ITSELF COMPRESSES TFC VERY CLOSE TO TWRS AND HAS LIMITED LATERAL BOUNDARIES. 2) I DISCOUNTED MY THOUGHTS OF DEVIATING TO THE S TOWARD THE FRZ UNANNOUNCED BECAUSE I DIDN'T WANT TO ALARM ANYONE WATCHING THE RADAR. I DISCOUNTED MY THOUGHTS OF CLBING UNANNOUNCED DUE TO THE CLASS B. NEXT TIME; I WILL NOT ALLOW THE SITUATION TO PLAY OUT. I WILL UTILIZE MY PIC AUTH; SQUAWK 7700; AND DEVIATE. NOTE: I RESEARCHED THIS PROB AT TIPTON USING THE ASRS WEBSITE. IT'S HAPPENED BEFORE. HIGH WING ACFT HAVE TROUBLE SEEING TFC CRUISING IN THAT AREA.