If every thing looked like it was legit and the pay rate was on par with other sites then I would probably give them a chance. You still need to do your due diligience and research them as much as possible.
I agree with pinkteddy’s advice. There’s nothing wrong with trying a new site out, so long as everything appears legit, but a site that doesn’t already have a well established clientele might not garner as much income as more well established sites. Try the new site out if you want, but don’t neglect the established sites you’re already working.
I would actually probably not try a start-up site because I have done it in the past, and it did not work out well at all. If you are going to try one make sure you check it out really well before you sign up.