Just for a data point, I use 2 5645's on a long Y to drive elevator. One of them was reversed for free by Hitec . I use a 6v pack and a Futaba PCM reciever. Works fine. Identical motion even though I haven't tuned the servos beyand what Hitec did for me.

The only time I had a problem was before I had the servo reversed. I was using one of those reversing y's, and it didn't work out. Gave similar result to those shown here.

BTW - no worries on current draw on these puppies. I just read the test results published in the sailplane column of Model Aviation from February. These things draw a rediculously small amount of current per oz-in of output. Lower than the other digitals AND regular servos tested(like, half).