Why a 6-inch F/15 Refractor? From my years of experience as an astronomer who has used a variety of telescopes of different types along with using very rare large apertures of 8-12 inches. I have found the 6 inch F/15 refracting telescope is the optimum design for lunar, planetary, and solar observing. The telescope's size makes it the best instrument in my opinion for advanced observers to use and simple enough for elementary observers to use for their viewing. An observer can master the telescope system with relatively few instructions, and yet the system is large enough to provide optimum viewing in city astmospheric conditions. Furthermore for more advanced observing the 6" F/15 refractor with it's accessories provides opportunities for photographic and spectroscopic work as well. Observatories and educational institutions usually have found the 6-inch F/15 refractor to be the finest instrument for lunar, planetary, and solar observing. For those wanting to build a 6" F/15 refracting telescope system for their observing should obtain a copy of "Telescope Making#44" and read the article entitled "Constructing a Large Brass Refractor" by Larry Myers. Telescope Making was a publication of Kalmbach Publishing Company (Astronomy Magazine)

...but but but where is the 6"F/8 posting that has famous on the net? Where is it Loron. Ok it's a troll thing.

While a 6" f15 may or may not be the best scope for planetary (you'll get a lot of arguments from owners of 16" Newts that are more portable), the mount has to be considered. Because of its weight AND length, you'd need something like the Tak EM400 or bigger to handle it effectively. You could mount it on a CGE, but the slightest breeze will make high power viewing (read planetary/lunar) all but useless.

Then there's the observatory to house it. My 8'X8' roll off works well with my scopes, but would be useless for the big refractor. More expense.

You'd be hard pressed to do a side by side comparison of a 16" premium Newt next to the big refractor and say that the views of Saturn or Jupiter are better in the 6". First of all, the big refractor couldn't handle the magnification of the big Newt. This is an unfair comparison, however.

Also, in your post, you mention "yet the system is large enough to provide optimum viewing in city astmospheric conditions." Are you saying that big aperture in the city isn't as good as small aperture? Not true. I've been doing this about 4 years, but have viewed under just about all conditions possible. Regardless of the amount of light pollution, big ALWAYS shows more than small...always.

My favorite example is my typical suburban backyard. My Megrez 110 can't find M74....too much LP. However, the big SCs that I've owned (C11, C14, 12"R) and the current scope (VMC260L) show M74 clearly. My Megrez is my outreach scope. I always setup next to a big scope, usually a Newt, for the participants to see the size difference and the view difference. The big scopes always put the Megrez in the garage.

Aperture is king for visual. You can't change the laws of physics. Yes, a good (and very expensive) refractor has terrific contrast, nice dark backgrounds and those pinpoint stars, but looking at Saturn through a big, cooled and collimated Newt and the view is extraordinary.

I had a 6" f8 achromat. I had a great time with it. Then I went to an outreach and set up next to our club president that had a C11 on a G11. We both traded views of Jupiter. I sold the refractor and haven't looked back.

However I think the 6"F/8 refractor is better.