It's not as easy to perfectly position a planet at the outer edge of the sweet spot on a high-power EP as it is with slow motion controls.
Yes, it is. It just takes a little practice with the mount
Well I should have stated: "It's not as easy for me to perfectly position.... - this is not a practice issue as I've had my DM-6 for a couple of years and I don't think I need any more practice on it - it's a matter of personal preference. You can't have your cake and eat it with a mount like the DM-6 - you can adjust the friction so it's buttery smooth, but then you run into issues when swapping EP's (which I do rather frequently), so I need to crank up the friction enough so I'm not constantly taking out the wrench to adjust it (I would find the DM6- a lot more useful if there was just a knob on the outside to adjust the tension). The advantage of a mount with slow-motion controls for me is that I can have the friction high enough so I can swap even a 31Nagler with a small Ortho without having any re-balance issues, while still having micro-smooth adjustments via the slow motion controls.
With the DM-6 tensioned to allow the same EP swap, I find when viewing at 250x+ that it is not easy at all to get an item perfectly positioned and I've had several other observers try as well with no more success - YMMV - but this is definitely something that each person should determine for themselves as you will find much disagreement on this issue. And only those people who have spent considerable time using both type of mounts are in a position to really judge the relative convenience of each style of mount.
I was referring specifically to my experience with the DM-4 and I apologize if my comment splashed over to your experience with the DM-6. It was unintended. I agree that everyone's mileage varies and that one's preference is based, at least in some part, upon what one is used to. I'm just wondering if your experience with your Teegul and one of your lighter scopes (I assume you don't mount your NP127 on it) can readily be up-converted to the DM-6, a wholly different animal capable of handling weights up to 50 lbs. Even if, hypothetically speaking, slo-mo controls were added to the DM-6, I wonder if you could even turn the knobs with a 30-40 lb scope on the mount? I suspect we'll never know.
Anyway, holding a fast moving planet at high powers constantly at the center is probably the most difficult thing an observer with a push-to mount can do. As I understand slo-mo controls (and from some hands-on experience with them), one control moves the scope up and down and the other moves it right and left. So, unless the planet is moving solely in either one of those directions, you need to operate both controls simultaneously to track it so as to keep it constantly at the center (I presume that tweaking first one control than the other would allow the planet to drift off-center in one direction or the other). Assuming for the sake of argument that this (with possibly an occasional re-focus tweak) is easy enough to do with your Teegul and one of your lighter scopes, I don't see this as being any different than what I accomplish with my DM-4 and SV105. I just need one less hand to do it. Again, as you suggested, a preference based upon personal experience.
Lastly, I'm very surprised you need to adjust friction for an ep swap. I don't have to do it with my DM-4 and the DM-6, with its larger friction plates, is way less sensitive to weight changes than is the DM-4. Is your scope balanced properly? If it isn't, repeated increasing/decreasing the friction won't cure the problem (only makes it more annoying) and may be contributing to the matter you described of holding planets at center. You really should talk to Tom Peters about this. I picked up my mount at Tom's place 4 years ago and he spent about 3 hours with me balancing up my SV105, showing me how to use the Sky Commander, talking astronomy, etc. Since then, I've had re-balance one more time after the friction plates broke in. Regardless of whether what I've described is causing what you've described, it is certainly worth a call to him to find out.
Sorry about the long post but it can be blamed upon the near constant rain we've had here for the past week. Hope your Memorial Day is fun...and dry!