Both are very worthwhile. Setiemson's Auto-Haste is the best positive status condition in the game. Rubber Costumes are actually the best armor for Engineers, Chemists, Soldiers and the like. Essentially any job that doesn't normally wear heavy armor benefits tremendously from the Rubber Costume. Although the name sounds a little kinky. For yuks and giggles try equipping Cloud with a Ribbon and Rubber Costume.

I've never had a problem with equipping Chaos Blades. They only seem to petrify the units that get hit by them. Now the Stone Gun is another matter. It petrifies it's wielder at the beginning of the battle, no matter what protective gear they wear. You're better off with a spell gun.