I could see cashmere or camel hair or some kind of soft solid, but I just think two hard-finished tweeds might not work for me. I haven't tried it, so of course I could be wrong, but the idea doesn't appeal in the same way that tweed/flannel or tweed/moleskin does. I guess if both tweeds were particularly refined, then it would work alright. The brown herringbone with the light gray donegal could be great, actually. I wish I could go all flannel, but I think all moleskin would be more my speed.