Hi Adam,
They are correct that quality over quantity however I would be cautious over signing contracts for 6 months, I don't meant to toot my own horn but we don't lock you into contracts at Pixel by Pixel because they can be unfair.
It's pretty easy to look at links and call wolf on them even if they may not be "toxic" Unfortunately research is part and parcel of SEO however it shouldn't really take a month. I'd more look at it in terms of hours. Whilst they might be in terms of months how many hours are they going to be working on your site as it may be a month but if they are only putting in an hour a month is it worth it ?Ask to look at some of their previous work see if they can back up their claims
I would also expect good communication its very common that SEO firms get you to sign a contract then vanish with the odd print out report with no real human interaction as to whats going on.
Whilst it takes them a month to look at your SEO back links don't skimp out researching them.Don't forget you can shop around too!
Good luck