Just been reading a lot of stuff on this forum that discusses Aikido and BJJ and how they can "help" each other.
So I'm curious.
Aikido is the art derived from Samurai Jiu-Jutsu, the foundational art of the Samurai who were sword-wielding, armour-clad death machines who needed to not just ground themselves to be the base of their swords, be as heavy as a mountain yet as swift as a river, but to be able to still fight tooth and nail if they ever lost their sword, against other sword-wielding, armour-clad death machines. In facing impending and greusome deaths, Samurai spawned one of the greatest Masters of all time, namely Miyamoto Musashi who not just produced some of the greatest martial strategies, art and petry in Japanese history, but also master fighting (ACTUAL fighting as in "I don't like you. I'm going to cut your head off now.", with not one but TWO kitana simultaneously...
Aikido is actually based on Daito Ryu. Daito Ryu does not (to my knowledge) include training in armor and does not have to include any more real swordwork than aikido. Also, if you watch the posture and movement of aikido and Daito Ryu and compare it to older budo that actually has kata with armor you can see that the older forms have a distinct way of moving (ex very low stances) thatīs not reflected in either aikido or daito ryu which rather promotes a very straight posture. Also there is a lot of practices in older budo (ex forms of grappling) thats not included in the aiki arts. So your basic premise that "samurai fighting arts" = aikido seems to be a bit sketchy.
BJJ is the Brazillian art (derived from Japanese Jiu-Jutsu) that fights swordless, armourless ruffians brawling in the street after a hard night on the piss, or those seeking fame and fortune in the media-fuelled cages that promote wealthy people watching poor people bash the crap out of each other. In not having to face impending and greusome death, BJJ spawned the Gracies.
Sure, bjj is not a art designed for the battlefield, but the Gracies were actually pretty wealthy and well educated. They treated jiujitsu more as a healthy lifestyle including a sensible diet (with heavy restrictions on alcohol). Many of their students as well since jujitsu was a rather expensive art to train in. You seriously need to read some interviews with some leading exponents of the art (ex Helio Gracie, Rickson Gracie or Saulo Ribeiro) before making up your mind on the subject.