I've got about three years on the Kinesis, and it's essentially brand new, aside from those wrist pads, which you can easily replace. I take it apart every few months to blow out the crumbs, and I'm also pretty amazed at the construction. It's very much designed to be taken apart and repaired, not just thrown away when broken.
I looked at the Maltron too, but the US availability is sketchy, and they're about double the cost of the Kinesis. I do like the real F-keys, but would probably remap the other modifiers you mention. (I use AutoHotKey already to remap some of the F-keys, using the Home and End keys as modifiers.)
I think the link was above, but if you really want to fall down this rabbit hole and spend a week or two obsessing over keyboards and mods, the geekhack.org site is the place to go.