you will lose a lot of superficial appeal: There are a lot of readers (especially younger ones) who have a bit of that childish 'ooh pretty colors' mentality, and will immediately become bored from a black and white comic.
The tradeoff, of course, is that you gain speed and efficiency, as you have already intuited.
I would also argue that if it's your first comic, you will gain a HUGE amount of invaluable experience from focusing on black and white. You won't have the crutch of color to make your comic readable for you. It's a lot easier to tell where the red-haired character is vs. the one wearing a blue shirt when you can color those elements red and blue respectively, so you don't have to think very hard about where you're placing your characters and making sure their shapes, poses, and designs are readable and easy to distinguish.
But I would also emphasize that if it's your first comic, then one of the last things you should be worrying about is readers/audience. That stuff just comes with time, and in my experience, there's really nothing can shortcut it except for astronomical luck. You're still a student, so it's probably going to be a lot more stress than it's worth to concern yourself with the size/growth of your audience right now.
What's going to get 'people' to read your comic is really a marketing question, not an artistic one, so worry about that question after you've reached the point where you're able to start marketing.