John, side by side photos and comparisons of the two TT-50 versions is an excellent idea. I will do that and try to have it posted sometime this weekend.
Antz, my very slow truing/dressing technique was a product of great frustration. My problem was glazing rather than being out of true. (I was reshaping a high speed steel turning gouge.) I had to use the truing tool so often that I dedicated a spare support bar to using it. (unnecessary most of the time). By the end of that project, I was very skilled with the truing tool. I could take both shallow and deep cuts with full control. It was like a Tormek boot camp, effective, but not very pleasant. There are better ways to learn.
A week in Sweden, under the watchful eye of an instructor like Stig, would be ideal. Using a well done in depth instructional video, like Tormek has produced for woodturners, is a strong second choice. Alan Holtham , Steve Bottorff, Knife Grinders (Wootz), and Sharpco come to mind as top tier you tubes.
Antz, I think your problem may be with your first pass. It sounds like later pass technique is fine. My gut feeling is that your first pass may be too deep. The first pass should just barely touch only the highest spots of the wheel. The diamonds should not touch most of the wheel. I don't see how one can cut gullies if the cutter doesn't make contact with the low spots.
As you become more proficient with truing, it should only take a few minutes. This will come with focused practice. Use your tuition money (your first grinding wheel) well. Knowledge and experience will make your future wheels work better and last longer.
Hang in there!
Ken
ps It seems logical that sharpening flat chisels and plane blades might tend to flatten the grinding wheel. The inverse is certainly true; gouges will certainly make grooves!