She is a lesser Elenia or elenia chiriquensis, catching flies in Tilaran. Lovely songs are in her repertoire as well, although the males are more vocal. She looks like a cross between a crested tit and a greenfinch and she is about that size.
So this is nş2 LBJ
Many thanks for all your votes on the elusive predator, feel quite chuffed that I found their hideout.
Cheers and thanks to Walter for his generous award.
Last but not least, SPECIAL thanks to Mike Young for IDing my grassquit, the last LBJ.