Touring - How high is too high

I am trying to figure out a good height for the handlebars on my touring bike. I am using a stem riser adapter right now that if I put the handlebars all the way at the top of the riser, the handlebars are about even with the seat or even just a little higher. The bike is incredibly comfortable to ride with the handlebars set up so high, but am I losing power on the pedals with a more upright posistion rather than a slighly bent over posistion? This bike was built as a pure road touring machine and I want comfort as a top priority but dont want to sacrifice effeciency or power. ANY opinions are greatly welcomed!!!

I always ride with my handlebar either even with the height of the saddle or perhaps even just a bit higher than the saddle. For my type of cycling, comfort is of vital importance.

I could be wrong, but IMO, I don't think you're losing any power by having the handlebars raised, you are however losing a bit of aerodynamics. However, if you're riding a loaded touring bicycle, you aren't the most aerodynamic anyway.

What Machka said. More info from an exercise physiologist here:

http://www.rivendellbicycles.com/html/rr_raisestem.html

If you are touring, and riding six or eight hours a day, comfort, and freedom from pain is more important than some imaginary "efficiency" measurement. If you look at were the bars were set on bikes used in the Tour de France from around 1930 to around 1980, you will see that even guys who raced formerly had their bars much higher than most bike racers use today. Maybe "old school" racers did not have someone available to massage out the painful cramps in their back and neck.

I like mine even, or just a touch higher than saddle height. I use a threaded headset, w/a Nitto techno stem (they're plenty long for up/down adjustment) so if I happen to get a bit of shoulder/arm/neck pain from too many hours in the saddle I'll raise it a bit more. Works wonders.