Truetrac is a torque biasing diff centre - I wouldn't write them off so quickly.
Quaiffe do a torque biasing diff,similar to truetrac,but I would thing much better quality.
You will get as many different opinions as people you ask,but I used a rear detroit in my landrover for a year or so,and thought it was great - no handling issues on the road and no clunking when disengaging.The only reason I changed to ARBs was because on very low traction surfaces the detroit would sometimes not unlock on a bend - which wasn't great for trialing.
Give the Kiaser a go,and tell us about it.