I always liked the lower placement on the top wing root fairing, for clearance coming into the hanger. Just enough aft of the rear spar to provide clearance for the cable connection.
I've been waiting for someone else to bring it up, but I don't see it happening. On my last project (certificated Cub), I installed a VHF-5I (Advanced Aircraft Electronics, Inc) fiberglass substrate comm antenna inside the fuselage (owner wanted NO antennas on the outside, he $ettled for the tiny 20 dollar whip for the xpdr. No nav due to GPS handheld bracket mounted on the panel), and have seen more than acceptable performance "down here" in the lower 48. Does anybody have any "high performance" experience with these? As in LONG range transmissions, send/receive? As I say, having excellant results "locally", but haven't had the opportunity to "reach out and touch someone". It presented some interesting head-scratching moments getting it installed inside the fuselage and getting it to remain "within 45 degrees of vertical", and had to settle for fudging it a few degrees when in the tailwheel is on the ground. Being a bit out of recommended installation orientation doesn't seem to effect ground communications in any way, even from all the way across the BEEG airport. Can't see ANY differance one way or the other when in flight from the high dollar composite antenna that used to be hooked to this same B-K KY-97. ATC says "nice and crisp. Loud and clear." when asked "how me"? Never more than 40 miles away around here, however (lemme up. its not MY fault!)