While the header image opacity settings work great for one sidebar or one sidebar on either side, there is no option for a two-step opacity for two sidebars on either side, e.g. one opacity for right sidebar and another one for right inner sidebar, is there?

This can be hacked,
in 3.4.2 you need to edit bfa_header_config.php and change line 284 from

			$header_image .= '<div class="opacityleft">&nbsp;</div>';

to

			$header_image .= '<div class="opacityleft">&nbsp;</div><div class="opacityleftinner">&nbsp;</div>';

then change line 288 from

			$header_image .= '<div class="opacityright">&nbsp;</div>';

to

			$header_image .= '<div class="opacityrightinner">&nbsp;</div><div class="opacityright">&nbsp;</div>';

next you need to add a CSS insert

/*-------------------- OPACITY LEFT INNER -----------------------*/

div.opacityleftinner {
	position: absolute; 
	z-index: 2; 
	top: 0; 
	left: 200px; 
	background-color: #afffff; 
	height: 150px;
	width: 200px; 
	filter: alpha(opacity=60);
	-moz-opacity:.60;
	opacity:.60;
	}

/*-------------------- OPACITY RIGHT inner----------------------*/	

div.opacityrightinner {
	position: absolute; 
	z-index: 2; 
	top: 0; 
	right: 200px; 
	background-color: #afffff; 
	height: 150px;
	width: 200px; 
	filter: alpha(opacity=60);
	-moz-opacity:.60;
	opacity:.60;
	}

making sure to adjust all the numbers to match what you want - the #afffff will give you a light blue/green so you can see where it is

Thanks. Not sure I will try it yet, but it's nice to know that it can be done. A donation is on its way