but gear systems have got flimsier and more fragile as more cogs have been added.
I'm with clubber on this, IME this isn't true at all, my 9 speed stuff is fine, maybe once or twice in the deepest depths of winter the 11t or 12t get clogged, no biggie, haven't noticed a particular increase in wear or set up hassles either, in fact I'd say Shimano stuff now is easier to set than it used to be. I'm intrigued by 2×10, I'd want to have a go on it before splashing the cash though, and like normal, I'll wait for a year or so to make sure it works.
Did do 2×9 for a while with a Middleburn duo, couple of things I noticed, Duo chainsets are pretty bendy, and you tend to chase the ratios a bit, and each change from big to "middle" was a bit of change-a-thon, but that was again a ratio issue. If those are sorted out, then can't see that 2×10 wouldn't be OK for most folk..