What does versatile mean? It means, when it comes to scopes, that a telescope can do a variety of tasks and do them reasonably well. The f9.8, 4" is the more versatile scope. It is not too big to be used as a grab and go, judging from the comments from users on cloudy nights. It is capable of 2.7 to 2.8° views (think nicely framed Pleiades), while showing more detail and better contrast at higher power. An f6.6 is not a generalist's scope. It is a specialty scope.
Furthermore, when it comes to extra purchases, the diagonal that comes with the f9.8 instrument at least will be sharp at 100x and higher. If you can live with the 1.6° field limitation (think shoe horned Pleiades), the extra purchases for a beginner are minimal. I personally think the Omni XLT 4" (with a CG-4 mount) at $450 is a better beginner's scope that the AZ version. It does more and is more stable. When you factor the extras you have to buy, it's not really much more expensive.
That may be reasonable definition of versatile. I would say a versatile scope is one that does an adequate job. From my point of view, having owned both, the only thing the 4 inch F/10 does better is planetary and double stars. Otherwise, the 4 inch F/6.6 just does more things.. It can be used terrestrially, it's a super finder in comparison to the F/10, star hopping is the biggest challenge for a beginner and the 102 F/6.6 on an Alt-Az mount is certainly much better for star hopping. The whole rig is definitely easy grab and go. The 43 lb XLT.. not around here...
So, from my point of view, if a beginner wants a telescope that performs at high magnifications and is willing to sacrifice portability, an 8 inch Dob is the obvious choice. It will run circles around either of these scope for any object that fits in the field of view. For a beginner that wants a telescope that is easy to use, easy to setup and a scope that is intuitive, that is easy to star hop with, a telescope that can be used to look at the mountain in the distance or a bird on a telephone wire across the way.. This one should do the job.
Part of the difficulty here is that you began thinking this was the old 102mm F/5 on the AZ-3 mount. I have owned that one, it is definitely more limited, the mount is really best suited for terrestrial and at F/5, it's very fast and the false color is significant. But at some point it became clear that this was not that scope. First came the scope itself, F/6.6 rather than F/5.. A definite improvement in making it a better all around scope. And then, after some coaxing, you realized that the mount is not the old AZ-3 but rather an entirely new, balanced mount with gear driven slow motion controls. Quite a different animal. It's an entirely different package.
This review is about the 102mm XLT AZ, reading wargrafix's review would have revealed that which scope this really is, saved us both a lot of trouble. I was like you, I thought it was that old F/5.. But I found out different. I would like to concentrate on the 102mm F/6.6 and finding out what it is, what it can do... There are plenty of alternatives to discuss but this thread ought to be about this scope and not some other scope.
Jon
PS.. a 1000mm focal length means the maximum possible field of view, 2.64 degrees with a 2 inch diagonal, 1.60 degrees with 1.25 inch diagonal.. Field stop calculation.
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