Dave, I checked LowePro's site for the LX160; they list an EX160--is that it? It looks like a fat briefcase.
I wonder if a smaller Domke bag might be the ticket for you, such as their original F2. Its footprint is rectangular, and its cross section through its short dimension is roughly square. Its interior space can be left open or partitioned by dividers/containers that velcro into place. It has a boatload of pockets and crannies for all your smaller items. I think the F2 has a zipper pocket running the length of its backside, but a check at B&H or elsewhere would verify this.
I have gone the usual route of trying/buying/selling bag after bag, looking for one does-it-all solution. (Like your situation, local stores don't carry anything other than LowePro.) Doesn't exist IMV. like most of us I found that bags that are good for storage and protection aren't so good for working out of and vice versa. My last bag was a LowePro Commercial AW MF, a cavernous heavy monster that protects like a presidential secret service detail, but sacrifices portability and access. It's now sitting empty.
If you aren't familiar with Domke, it seems they aim for usability and access, with just the amount of protection needed and no more. It's minimally padded but in practice i've not found that to be a problem.
I have the larger one, the F1x, in canvas; in it I carry a Contax 645 with a Kodak ProBack and up to four lenses, with smaller accessories arrayed throughout its many pockets. I have taken out the divider section that came with the bag (its "silos" are too small for my MF lenses) and simply put the lenses' own bags in there, open so they are easy to get to. All of this stuff usually lives in a Pelican case for storage and protected transport. The Domke takes what I need for the job or the day. I have no complaints at all about it--best and most usable bag I've owned, overall.
The Domke's strap is especially nice--it's wide and has rubber stitching or threading of some kind running its length which enables it to grip like mad. It won't fall off your shoulder easily. (I've outfitted mine with their accessory foam-rubber shoulder pad that velcros to the strap.)
Only downside I can think of for you is that the canvas is not waterproof, so you'd want a ballistic nylon version instead. I like the feel of the canvas, and wanted a color other than black.
I know Domke makes some other bags that are more like messenger bags or briefcases in shape, so that might appeal to you more.
Another thought might be Billingham--people here and elsewhere swear by them.
Hope this has helped.
