Welcome to the boards.
Normally I would ask you to provide more information on the type of league (h2h, roto, points?), categories, etc however:
You're giving up depth (which you have) for a high end D (which you need) and a buy low forward who could still thrive in the right situation (bonus). And you're creating space that you need.
In future, it's best to provide as much information as possible about your league type, categories etc to get the best advice. Good luck.