The Birkenstock felt clogs have been replaced as the work shoe by...
The Clarks Desert Boot
Damn these are almost as comfortable as the Birkenstocks, except fully enclosed. Wool wasn't exactly ideal...
To replace the Birkenstocks in the daily wear clog role, I have a pair of Birkenstock black Boston clogs (same shoe, black leather) on order. Most likely to be the daily wear shoe, won't be as hot as the wool.
Those desert boots seem pretty damn tough and durable, although the gum sole picks up everything.