To be honest I avoid most re-buy MTT's but if I do play one it's one like yours here. Only one re-buy isn't a bad thing.
If I havn't used my re-buy I play top ten and call any all in. I don't want to re-buy at all if I can get away with it. Ideally I want to triple up by the 4th round.
However with the blinds going up so fast Doing the auto rebuy after the first hand treating the MTT like a freeze out might not be a bad play if you think you can keep from getting caught up in the all in game that is going to be happening the frist 4 rounds.
As for the $10 add on. You are getting T300 for $10. T1000 for $50. you get T100 more chips for your money then you do in the re-buy so it is worth the $10.
Good luck and let us know how it goes.