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the 10:1 focuser has finer motion control over the stock focuser, which is more helpful for the "faster" (i.e., short f-ratio) 10" (an f5 I think) compared to the 8" (f6 I think). The shorter f-ratio scopes have a steeper light cone as the image converges at the focuser, and as such the sweet spot of focus is smaller. Thus, a finer motion controlled focuser will allow you to find the sweet spot of focus more easily. It's nicer with any f-ratio scope, just incrementally more useful for the faster f5 than for the f6.
GSO (Bintel) just changed their stock gear to include that 10:1 with the faster (larger) scopes. My 12" came with the regular focuser just last year; it's not a big issue w/r to enjoying the scope. More importantly, if you can afford the larger aperture and can transport/set-up/use the larger scope without difficulty, always go for the larger aperture. 10" is not "too big" for a starter scope provided you can handle it physically and economically.
I'd say the GSO EPs are good value and very successful for a first set. Having at least two (one low power and one high power) is probably best, three is better for a good spread across the mag factors. Odds are as you progress you'll gravitate toward the more costly premium products, one-by-one.
scott
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