My Terra is a declawed cat and let me tell you, she still climbs just fine. She doesn't climb the curtains anymore, but she can manage her cat tree just fine. In fact, her favorite place to be is "up". Up on the couch, up on the entertainment center, up on the cat tree, you name it, she can get there. She also still tries to sharpen her claws on the scratching post and rugs all the time.

As far as not being able to defend herself as well if she gets out, well, that's true. You'll just have to be extra-cautious that she doesn't get out. It'll be difficult (Terra is the only one of my 3 with any kind of wanderlust and of course she's the only one who's declawed) but you can do it. Just find the treat that tempt her the most and keep some on hand should she ever get out.

But these possible risks are far less than the guaranteed risks if Mia does not get declawed from how it sounds.