Hi darwin
I'm only 5'8" and about 165 pounds myself. I've always considered myself pretty strong for my size but like you, the WR wore me out when riding hard in tight woods. I feel like my riding ability improved almost over night, and my riding buddies have noticed the difference also.
You do have to shift more often on the 200 but it doesn't bother me a bit. I don't feel like it is excessive by any means. The 200 has so much low end power that I usually ride it a gear high, especially on slick hard pack. Even a gear high, it has plenty of snap, but if you want more just touch the clutch and away you go.
The stock exhaust on the 200 is quite good. You definately don't need to plan on changing the exhaust right away. It can always be customized to suit you but it is a real good exhaust system. The only draw back is that the stock silencer weighs about 5.5 pounds. I personally did not plan on spending any money on the exhaust but I found a deal I couldn't pass up. I bought a used stock 200 exhasust to customize for $40.00. Mike Lafferty and others have cut the spark arrestor out of the stock exhaust and shortened the silencer by about 5-6 inches. I modidified the one I bought, but my broken finger hasn't allowed me to try it yet. It's suppose to give it even better bottom end plus you shave 2-3 pounds off.
Other mods that you should consider are guards, such as; hand, pipe, skid plate and clutch slave. The stock handlebars are as good as Renthals and the chain and sprockets are also top notch as well as the wheels.
Selling the WR and buying my 200 is the best move I made. No regrets.
Neal