Looks spot on to me.

Agreed. Dr Osterzen (guessing that won't stick but I'm throwing it out there anyway!) is categorically going to be a tough, tough figure to take down. But he's a long way from being unbeatable, or requiring that the opposing team be specifically built with him in mind. As Gatharion said, the "stealthed PB-er" is by no means the only way to inflict some hurt on him.

Also, it's worth noting that, as a matter of course, a fair number of opposing teams will also have one or more PCs (to counter-act his own rerolls) and/or Perplexes (to make the attack roll more palatable to begin with). Taking that into consideration, we're probably closer to the 40/60 mark for a 10AV figure to hurt him (that's just me eyeballing it, to be clear - apologies for not having the inclination to go through the math, but multiple PCs are where it starts getting a little tricky for me )