Big arms are very overrated. I'm also 5'9" and about 175lbs currently. If I were to ever fight mma it would be at 155.
I've been bulking for probably 4-6 months, and I gotta say my arms are a lot bigger but I am noticeably slower than I used to be. Not to mention my arms get full of blood fast and takes off even more explosiveness. But I look damn fine as I do it
(might also be the creatine my muscles feel semi water logged sometimes)