I'm interested in studying grappling, locks, throws. Basically using my size (6'4", 280 lbs, no fat) to my advantage. I already hold a 3rd dan black belt in Goju karate, but karate in general does not make use of a person's size and weight. And too many street fights end up on the floor, so I'd like to know how to fight effectively on the floor. BJJ seems to stress floor grappling more than traditional jujutsu. Can anyone shed some light on the difference between the two?
There are many classic styles, so you might check out what the locally available styles do.
The japanese jiu-jitsu style in which i train focuses on standup grappling and controlling or pinning an opponent afterwards on the ground. We do almost no takedowns but a lot of stand-up locks and throws. Because of that our ground-training is mostly with us on top in a better position. So if you realy want to grapple and be good on the ground, i suppose you better go for BJJ.
Please note, that my traininggroup is located in an police-facility and therefore probably focuses more on pinning/handcuffing somebody than other styles.
Another difference between japanese and brasilian jiujitsu is that strikes are incorparated in the japanese style. But as a boxer i also have to say, that only teachers with an additional striking background (have seen many masters, with black belts in karate) do incorparate decent strikes. The thing with the striking is, that there are are many jiujitsu people, who can't strike well and you may have to train with them. So take the additional striking with a grain of salt and lookup your local people.
As in most cases, the people and teachers matter more than style.
I can only compare JUDO with bjj. there are handicaps on both for your intended purpose, bjj stresses a lot on groundwork it has great locks and submission techniques but is somewhat lack in on the transition from standing to groundwork. JUDO on the other hand has lots of standing to ground transitions that by themselves will put the opponent out . in the ground however bjj has more solutions and many JUDO practitioners are easyly surprised with locks to joints other than the elbow.