HELP!

Looking at a 2003 Summit 700, 144" Track with 2" Paddle, about 5000 km... Any body have any advice on what to look for, weak spots, problem areas..... also wondering what the compression should read when tested..... are the 700 engines good on gas in comparison to other machines?

For compression you would be looking more at how even the cylinders are. You want them to be close in compression reading, this shows that they are both wearing the same and that one doesn't have a problem. As far as numbers go,(providing your comp tester is accurate) I would say you want to be over 130 at the least.
Problems or weak spots, nothing to speak of. That 700 twin is a very solid motor and pulls very strong.
It does, however, like to drink a lot of gas.

that's my .02 anyways

Check the rings, if the rings are original, they should probably be changed. Bullet proof sled though.