Can testers peer review the developers' design and code?

Question

I am a junior developer for a small business using scrum / agile development. A long-term goal of ours is to be appraised at CMMI lvl 2. We have a team of 3 senior developers who implement user stories and a handful of junior developers for support.

We are moving towards a "three amigos" methodology, especially in regard to separating the duties of development and testing (the third amigo being the product owner / business stakeholders). This way our senior developers can focus on implementation and our junior developers can focus as impartial testers.

We are using peer reviews as a specific practice for verifying work products, such as source code. This paper, http://repository.cmu.edu/cgi/viewcontent.cgi?article=1208&context=sei, describes on p. 19 that an optimal peer review process for design and code ranges from 50-65% of the time spent designing and coding.

My question is this: is it appropriate for our testers to peer review the developers' design and code? An advantage would be that the developers can spend more time implementing user stories. A disadvantage would be that the testers may sacrifice their objective/impartial view of the system, since peer reviewing creates a shared ownership of the code.