Wade
I bought a 12" GSO dob in July last year and love it. Although a solid tube is a bit of a handful a simple $50 trolley and a bit of carpentry will make it much easier to move around. See
http://www.iceinspace.com.au/forum/s...ad.php?t=47433
Also I have made a couple of straps from Webbing and velcro that make it much easier to carry.
To your specific queries,yes they have a centre spot.
Mine holds collimation fairly well but I have replaced the springs with ones from a Bobs Knobs kit. As I have to wheel it down a couple of steps i always recollimate before observing, get a laser collimator, makes life really simple . Also definately get Bobs Knobs. Worth every penny!
The OTA is 1500 mm long, the base is 630mm diameter and 690mm high.
I use it a bit for planet, but that is not its strength. Jupiter is fairly good and Saturn OK, need perfect cosnditions and the right time of year to see much on Mars. The best thing about it with planets is picking up small satellites, I have seen Enceladus in mine!
The finderscope on mine is pretty good, does an OK job. Wouldn't spend money on another. Mine came with a 32mm plosll which acts as an intermediate finder when I need it between the 8x50 and my 24mm Pan.
I have found that if you load up the end of the scope too much (I have a telrad, a laser finder, big EPs, dew straps ) you have to tighten the tension controls fairly tight which makes the alt action a bit 'jumpy', Am about to attached some weights (magnets ) to the mirror end to try and smooth it out. The tension control system in these GSOs is a thing of beauty IMHO.
The Az motion can be very loose. When I first set it up I found if a gave it a push, it spun about 3-4 times. A coupla bits of felt slows it down a tad.
Alround excellent value for money as they can be picked up under $1k IMHO
Malcolm