I wouldn't worry how they feel honestly. Primary focus should be making your wife feel good.
This is a good response. I think it's really important to get to the real heart of why she wants them. Just because she's small? Because she's insecure? Because she hates her body? Because she thinks you're not satisfied with the titties?
You want her to feel good. Understand exactly why she wants them, and make sure she understands, too. It may be a knee-jerk reaction to something that's been triggering her for years.
Body alterations need to be done with plenty of clear thought in advance. You don't want her to get to a point in a few years where she's asking why the hell she did this to her body.
I'm not a fan of big, fake titties. My wife's boobs are small, and having five kids really did an unbelievable number on them. She's asked if I wish she would get them done, and I don't want her to. I'm very attracted to my wife's body, and I demonstrate that, and she's secure in that. She, of course wishes she looked like she did when she was 20, but she is also a self assured, confident person. If I were really pining for new tits for her, she might be motivated to do it. But I don't need or want that.
Anyway, talk to her and make sure she's fully aware of why she wants to do her boobs. And if you guys do decide to go ahead, be sure to take and post before and after shots. For science.