I feel similarly Bubo, though don't have the multioption res. Next time the loop comes apart I'll screw the valve directly to the T, and keep a length of tubing with a barb on the end lying around somewhere. So screw the tubing into the valve, open the valve, done.
Of course, the valve will be connected all the time, but it avoids the siphoning and removing blanking caps. So I guess it's a compromise between the standard drain line and your proposal.