VFR ACFT DSNDS THROUGH IFR ALT. NO TA FROM CTR.

Narrative

I WAS ON IFR FLT PLAN. VFR AT THE TIME; 3-5 MINS BEFORE I WAS IN AND OUT OF CLOUDS. A LOW WING AIRPLANE (I THINK AN SMA) CROSSED MY PATH IN FRONT OF ME FROM R TO L. NO TIME TO REACT. AS I LOOKED OUT MY L WINDOW; IT LOOKED AS IF HE WAS DSNDING. I'M NOT SURE IF HE EVER SAW ME. THIS TOOK PLACE AT 11000 FT. CTR NEVER RPTED ANYTHING. I KNOW THEY ARE NOT REQUIRED TO SEPARATE IFR AND VFR TFC. I WAS TOLD THAT EMPHATICALLY AT A PREVIOUS TIME WHEN I CALLED TFC NOT RPTED BY CTR. MAYBE THAT'S WHY I SAID NOTHING TO CTR AT THE TIME. THE MORE I THOUGHT ABOUT HOW CLOSE THE INCIDENT WAS TO BEING REAL SERIOUS; THE MORE I WISHED I WOULD HAVE SAID SOMETHING. YOU DON'T WANT TO GET PEOPLE IN TROUBLE; BUT I WANT A SAFE ENVIRONMENT IN WHICH TO FLY. I THINK CTR SHOULD BE REQUIRED TO CALL ALL TFC FOR IFR FLTS AT LEAST ABOVE 10000 FT. IN ALL FAIRNESS; I REALIZE THIS DOES NOT HAPPEN OFTEN; BUT IT ONLY TAKES ONCE. THE PLANE XING IN FRONT OF ME WAS ABOUT 12 INCHES LONG IN MY WINDSHIELD; IF SOMEONE KNOWS HOW TO CONVERT THAT TO FT. IT WAS TOO CLOSE FOR ME.