The 4X6 is far superior in HEAVY trash than any other option IMHO. I use it a lot in several trashy parks in my area. The difference between it and the standard 9.5 is like night and day. Surprisingly, the 8X10 works better than the 9.5 in trash as well. I wouldn't have thought so, but have used it enough to become convinced. I guess the detection pattern is narrow enough to slip by some of the trash. Its sort of become my standard except for really heavy junk.
HH
Bill