The "AS350," or Astar is great helicopter, but you are right, it's a big step up from flying a Robbie. I assume you're flying an R44? Much bigger, more power, different visibility, more people...
At 500hrs - depending what type of flying you've been doing, and will do in the Astar - you should have a reasonable enough grasp on the machines to make the switch. That said, flying the Astar will open up a whole new set of jobs that you may or may not have experience with, and that requires a lot of decision making and judgement. I wouldn't say don't do it, but I would council caution.
If you can let us know what type of work you're doing now, and what the Astar work would be, I can give you a bit better answer. 500hrs is not 500hrs if you know what I mean? Oil patch or mountains? It makes a huge difference.