Cloudy nights did a review (my journey to astrophotography over several years - parts 1 and 2) about 2-3 months ago. In part one it had an interesting segment on the persons reliance on adaptive optics and it actually sent him backwards - disguising other problems and limitations in his set up and methods - after spending US $1,500 for the AO-7 I believe.
It's well worth a read to include in your thinking.
http://www.cloudynights.com/item.php?item_id=1647
excerpt -
The first wonderful piece of advice I got (and ignored of course) was to not use the AO-7 and simply use the camera and guider directly into the CGE. But I thought, “My CGE
needs the AO-7 to get good tracking” and used it right from the beginning. The trouble was for the first few months my tracking was 50/50. Some nights it worked flawlessly and other nights it couldn’t keep the guidestar for more that a few minutes. Then I found and read Mike Dodd’s excellent article that explained auto-guiding in detail, located on the Yahoo Group “CGE-Uncensored”. From then on I had no issues with guiding and it worked flawlessly every time. One major issue solved but the AO-7 still was having a detrimental impact on my images but I didn’t know it yet.
...
The biggest revelation came in December, a whole 8 months after starting this endeavor. In one of the CN threads a link was given to Richard Bennion’s presentation at an imaging conference. I watched the 45 minute video and all was revealed. I learned that my collimation wasn’t good enough, my star distortion was an issue, my focus wasn’t quite good enough, and how important all of these pieces are to the final image. I removed the AO-7 to improve the overall image quality because the focus point with it was near the extreme back and without it was much closer to the middle. I spent days playing around with collimation trying to judge exactly why my stars were slightly oval and got them spot-on circular with the brightest point at the center pixel. I was finally able to get FocusMax to work extremely well and understood what HFD means and what my typical HFD values should be on good nights and bad nights.