Just a comment: I can't say enough about the optics of my 12" Dob. Just superb! I wish it was lighter....maybe made from aluminum or carbon fibre or fiber glass, but in terms of observing, these bargin basement Dobs, dollar for dollar, are awfully hard to beat. If it could be done without dramatically increasing the price, a split-tube, fiber glass version would be ideal. Snap the two ends together....check collimation....start observing. Simplicity in the extreme. The drawback of the solid tube is size. I use the shipping box as a container......requiring a mini-van to transport it. At home this is no problem.......simply carry out the base, then carry out the tube and set it in the base. Size doesn't matter......although weight may be a problem at some point.
The large truss-Dobs certainly go a little deeper, but matched with the right eyepiece these old fashioned solid tube, "cheapo's" are not far behind......and much less hassle to set up and use......when time is limited, and you're in a hurry. The truss scopes do have the advantage of smaller size when broken down.....makes for easier transport. I have never looked through a really large Dob.....20"+ to 30". I suspect the views would make all the hassles worthwhile.....even the stepladder needed for observing.
I hope the basic Dobs don't disappear from the market. I see that Orion has stopped offering their basic XT 12. 10" is the largest basic Dob they offer. To get 12", you have to buy their new truss-Dob or the Intelliscope version of the solid tube. I suspect others will follow. A shame!!! If you want aperture on a budget, they fill the bill, with very little compromise in performance.
At any rate, I am totally happy with my 12". I would recommend one without hesitation.