Andyj45 - 
Sharkbait - Good question dude.
Both have advantages, I'm 6'2 and 160 pounds, lanky as hell, so ill give you my take on long and thin.
Adv: like you mentioned, weird angles and side/darce chokes become more available from different positions, top or bottom.
Triangle Chokes, my favourite. With legs like a freakin water bird, I find it very successful when attempting and locking in.
Flexibility: if I was to find love with another man, he'd enjoy it. I've always had great flexibility in my joints, doing splits, legs over head etc comes very easy
Disadvantages : can get folded like a pretzel and muscular size is quite a lot smaller than a 5'8 160 pounder
6 of one half a dozen of the other I guess, it's how you use it to your strength Phone Post 3.0
With you until flexibility Phone Post

LOL seriously, what's wrong with you????