Cost Seg Company - Should I shop around? Recommendations?

[Keetaek Hong]

Short: Can the Cost Seg Study result vary based on "WHO" does it? Should I shop around?

Long:

Thanks to my awesome CPA, I've learned about STR Loophole and embarking on the first cost-seg study. As a noob, I wasn't sure if cost-seg study varies based on which firm does it. Or does it follow a strict guideline that I should find the firm willing to do it cheapest?

If I should shop around, what are the criteria/questions I should be asking? 

Lastly any recommendations??