I've optimized the Cube based setup, again, picture tells the story better. I bought a small quick release plate, in which the plate can be rotated relative to the base. This plate is far lighter than the 410 head for such, and it's far lower profile and thus, the whole setup balance very nicely!
So, the scope could be attached easily and it's very stable.
Close up shot of the joint:
And the sky is better today, so the image quality tells. After seeing this image, I know that alt-az tracking of the Cube is great enough!
No need to look back. This setup is just right for me, it's lighter, more portable and stable enough for indoor solar imaging. With the hacking on the black side, the scope can point out of the window easily, I don't even need that offset plate which I've to used during the summer for indoor imaging with my LXD55.
Originally, I planned to buy a ball head for the black side. I checked that there're some good candidates from ebay, and so I went out to the local shops to compare the price. To my surprise, the ebay price is cheaper and it even includes shipping!
When I'm about to give up, I saw that quick release plate, and I think it should even work better since it's lighter and less complex. Therefore, I shall live with this plate at the time being, and I shall see if rotation is enough to align both sides or not. Such an alignment is useful when I use both ends for observation and imaging.
I will be passing my LXD55 to a local friend tonight, now knowing that the Cube will work for me, I feel more relax for the transaction.
No need to look back now!
Now, I'm saying goodbye to any heavier equipment formally. :-)
My heaviest scope is just 7lb (Orion 100ED) but it could be held with a 4lb mount (Unistar Light + Gitzo G106)!