Installation was fairly easy (despite a poor RA connection plug - this was readily replaced by JMI). One major hassle was the main RA gear which must screw into the RA hub of the fork-mount. The supplied hub was too short due to manufacturing variations of Celestron scopes from that era. It took three different gear hubs before I got one that was long enough to reach the recessed area. The folks at JMI were very understanding and shipped each one off as soon as they received the old one back. A major head-ache with the extra postage and the talents of Canada Customs. (Despite NAFTA the Canada Customs can be a really bureaucratic maze of stupidity.)

Also, despite reports to the contrary the RA encoder still interferes with swinging the optical tube into the straight down position for storage. I live with it like that, as opposed to trying to remove the RA encoder every time. I'm afraid that with the encoder simply dangling by its wiring I may break a connection if I snag it on something while carrying the scope around in the dark.

As far as its operation is concerned, the unit works quite well. After calibration with 2 stars I can usually get objects within the field of view of my 2" 32mm Meade Erfle eyepiece. I find it just slightly more accurate than using manual setting circles, but of course you don't have the hassle of having to make sure your scope is properly aligned when you first set up, and I certainly don't miss having to do that little chore! The one quibble with my unit is the planetary alignment accuracy. Always a couple of degrees off despite my best efforts. The manual doesn't say whether to enter the local time or UT. I found through asking the question on the Internet that UT was the correct time input.

My one other complaint - the basic operation of the computer is not obvious, so I keep pushing wrong buttons. For example, to have the unit guide you to an object I would like to enter GUIDE mode, and then tell the unit what object I want it to guide me to. But the way the unit works, is you first have to tell it what object you're interested in by going to the CATALOG mode, select an object, and then go to GUIDE mode. Not a big deal, I suppose, but for me it's counter intuitive.

In summary, I'm happy with the JMI NGC-MAX unit and highly recommend it. In fact I've now installed encoders on my TeleVue Genesis mount and also have them on my Astro-Physics 400QMD GEM mount. I just have to remember to reprogram the encoder values for each mount. This is easily done as JMI gives out a sheet with all the encoder values for the various commercial mounts on the market.

It must be pointed out that the JMI NGC-MAX computer setup is not a true "goto". It gives you the directional instructions for going to the desired object. There are three crucial parts of the "two star orientation" of the computer when its first turned on.

First is the DEC=0 setting. Second, if you North of the Equator, the "first" star selected for alignment should be in the East for maximum accuracy, i.e. Vega or Altair at my house in the spring mornings. The second star should be at least 60 degrees away; and, I pick one in the West, ie, Arcturus. And when aligning on a star, the power should be 200x or even greater. When following these steps, the "warp" reading will be less than .5 which is considered the minimum desired accuracy.

If you want to get a warp reading of "zero", experiment with the DEC=0 setting. I discovered on my old C8 fork mounted telescope that a setting of the mark, just a tad off (half the width of the marker) made the difference between getting a .5 and a .0 warp reading on the second star.

I now follow the guide directional instructions to my desired object, M108, put in my 20mm widangle Televue eyepiece and there it is. Now I can go with any eyepiece/CCD I want, as I know I have it.

The above is "not" all spelled out in the manual as clearly as I have tried to make it here. The basics are there; but, the experimenting with the DEC=0 is not; - and, the manual talks about the telescope being west for the first star. It means the mirror being west of the axis, which means the star is to the East.
 

As a final aside - LEVEL your mount. The manual doesn't say to but it can make a difference!