He has a 150TOA with fairly heavy camera and feels that the mount is not stable, even though the package weighs just 55lb. I believe that the weight may not take into consideration the added weight of the dovetail assembly. The tube weight itself is listed at 44lb and if you add the camera and field flattener optics plus the refractor on top, plus the dovetail system, the total weight on the Dec axis is probably more like 60+ lb. The moment arm is pretty large for this combo, so we had to change the damping quite a bit.
Yes, it will feel somewhat boingy when pushed or disturbed, but I have put my own large refractors on the Mach2 and as long as you don't disturb it, the guiding is rock solid down in the 0.2 arc sec when the seeing is good. Right now I have a 12" Mak-Cass on the mount and the Mach2 handles it just fine and guides very well. Wind or no wind. I think Mr. Whang feels that it won't guide with some wind, but remember, the heavier the scope the more it will resist moving (force against mass - mass always wins). I had a 160 EDF refractor with my 10" Mak sitting on top, total weight far in excess of 80lb and yet it guided splendidly even with a good breeze blowing. The scope really didn't move unless I pushed on the end and then of course it bounced around a bit, just like the video that Mr. Whang posted.
Sometimes our feelings about something don't translate into actuality. If I had that 150 TOA setup, I would go ahead and take some actual images and see what the results are.
