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I have found that with my F4 newt collimation wasnt too much of a problem, get a good set of tools and you are set. The main thing that I would be thinking about is guiding/vignetting. With my rolled steel tube I found that guiding had alot of flexture involved, the futher your focuser is away from the guidescope the greater the problem as the steel tube flexes signifigantly. I decided on going for an OAG because it seemed to be the best option completely negating diff flex. This caused different problems, I decided to go with a large format OAG because the 9mm varients I had seen cast a shadow on the chip, which was not something that I wanted. I then did not have signifigant backfocus to use the larger OAG. The other problem I encountered is the more you have hanging off the tube the larger the secondary you theoretically need. This is less of a problem with slower scopes because the light cone is less sharp, what I mean here is the parralel light rays that enter the scope are bent in towards the focal plane at a greater angle the faster the scope. So the more of the cone you have in the focuser the wider the secondary and everything after it needs to be.
I have now moved the mirror up the tube to increase backfocus and I can get the camera and guider to focus. I am yet to produce an image as the weather has been ****house but I will post what It looks like as soon as i give it a crack.
I would be interested in seeing what one of these running a guidescope could do If all of the flexture problems were dealt with. If you were thinking of using an OAG with the system I would wonder if the extra price for the carbon fiber would be worth it, I would much rather deal with steel for modifications and with an OAG the expanding and contracting of the tube should not cause too many problems.
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