I just bought the 10" LX200 GPS with UHTC.
What do you want to do with the scope? Observe planets? Observe deep space stuff? Astrophotography? What kind of astrophotography? Piggyback? Prime focus? CCD?
What you want to do with it will help you choose. If you want to observe planets and brighter deep sky stuff and do some piggyback photography, you don't need a 10" scope.
With prime focus, you're using the telescope as a camera lens. 10" gets you an extra 500mm of focal length (2000mm v. 2500mm).
For pictures of planets and really large bright nebullae, you're better off with an APO refractor. You'll see a lot more color and contrast and get sharper images.
For fainter deep space stuff, 10" is better. You have more light gathering. If you want to split binaries better, you'll want the 10" scope.
Some things to consider:
The 10" scope is heavy. You have to hoist 62lbs up on the tripod. Then, you have to keep it steady as you find the hole and tighten the knob. The 8" scope is only 48 lbs. Those 14 lbs mean a lot when you're hoisting the scope on and off the tripod. When it's boxed, you have to move about 85 lbs around.
The 10" scope is bulky. It's more solidly built than the 8" scope. The difference in weight isn't just in the OTA. It's also in the forks. The box is so big, I cannot get it in the trunk or the backseat of a full size car (a 2001 Chevy Impala). I have to take the scope out of the box and lay it on the backseat.
The 10" scope is definitely not happy in a light polluted city. If you live in a city, even with a light pollution filter, strongly consider the 8" scope.
If you're short, consider the 8" scope. I set the tripod up by fully extending the legs. When I was setting the finderscope,I had to stand on a chair to look through the eyepiece when the scope was pointed toward the horizon. Granted, you can lower the legs and save a few inches and most of your watching will be well above the horizon, but just realize the 10" scope is tall.
Astronomics is right. Don't pick the largest scope you can afford. Pick the one you'll use most. You might wind up using a 10" scope less than an 8" scope because of the weight and the bulk.
I'm keeping my 10", but I was surprised at it's weight and dimensions. Others are, too. When I was setting up the finder scope, people jogging by the house would stop and remark how big the scope was. It's definitely an "attention getter".
Just a few things to think about as you decide.
Let us know what you decide to do.