i'm about 6'1 250, between 25-28% bodyfat, and I'm wanting to learn Ju Jitsu. Would my size be a hindrance or an advantage?

No.

Neither unless you are so big that you cannot perform techniques on your partners or you are so big that they cannot peform them on you, which is unlikely.

Different techniques have different movements that are done better by people of all different types. You will find some techniques that are hard for you, some that you will excel at... what you want to do is practice to ones that are difficult, and schmooze the ones that come easy.

Size is a definite advantage in groundwork, along with strength, so you can find a niche somewhere in jujutsu that you'll be comfortable with. If you learn good "kuzushi" skills, it won't matter what size you are, you'll have control of everybody's balance...

You big guys always gas me out when I'm mounted, your wieght just pushes all the air out of my chest.

Schanne, we had a judo clinic about two years ago, and one of the black belts that showed up must have weighed 350 pounds. When we took turns doing the techniques, he sat on my chest and I swear my ribs were hitting my backbone. My lungs are due to re-aerate sometime next week, so I know where you're coming from...

Dead weight beats skill every time...

Thats great.. I'm about to sign up for some judo class and I weigh 111 lbs.

This is going to be fun...

Put some rocks in your pockets, and stay in your own weight class That guy at the seminar rolled over me like an asphalt street roller...

Seriously, their weight is only an advantage in ground work, so don't start off discouraged... smile and jump in...

ya the only disadvantage u will have is ur size will make it difficult for smaller people to really push you hard. once you find someone to negate ur size and strength, you'll start to really learn something.

yes u will have a huge advantage on the ground, but not so much on ur feet.

cause ur tall, when doing shoulder throws u will have trouble cause u gotta get really low.

Small people have an advantage over you in many areas of throwing. Pretty simple reasoning, your center of gravity is higher and you're easier to throw as a result.

Also you will find in jujutsu (Japanese) your arm and leg movements may be larger than a shorter person's because of the length of your limbs. This can make you slower but not by much.

Remember these disadvantages are usually offset by other advantages such as increased reach, etc..