Hi again Scott.
Well yes, a big Dob is going to give you a brighter image of anything you look at. So much that you might need sunglasses to look at the Moon! Ouch! But the main issue with light grasp is being able to hunt down DSO's - Deep Space Objects - and the like. And on those rare nights when you can push the power up to the theoretical times per inch formula, the big Dob will be able to resolve finer detail on the planets and split very close double stars etc. I am going to get killed for saying this I am sure, but for planets nothing will beat the razor-sharp image that you get from a good refractor.
Each type of telescope has it's drawbacks and appeal for various types of viewing. Due to this I have 3 telescopes: A 12" Meade LX200GPS, a Meade LXD55 AR-5 refractor, and a 200mm f4 Newtonian. Each I use for different purposes. But for planets, the AR-5 is the one that goes out the door with me. I did a lot of research before buying this critter and, though I own a monster 12inch, the view of the planets through it knocked my eyes out! Razor-sharp.
Unless you have a bucket of money and can afford to get an apochomatic(3 lens elements) refractor, The AR-5 or 6 is an excellent choice. The only problems with the 6inch is that the LXD55 mount is at it's limit with this scope, which weighs in at 27 pounds. Some minor and easy modifications can be made to strengthen same. And being a f8 achromatic refractor, there is some chromatic abberation. This can be countered with a negative-violet filter. I recommend the ones from William Optics. The AR-5 is fine on the mount and at f9.3 I have not seen any chromatic abberation at all. It's a trade-off for that extra inch of aperture.
If you want more info on these scopes, and their pricy apochromatic brothers, their is a group of very nice and knowledgable folk on Yahoo devoted to them I suggest joining - FREE of course - at:
They know all the tricks such as tweaking the mounts, collimation, after-market improvements, etc.
Better hurry! Mars is getting closer!