I am now a 500 ton master, So happy I got that over with. 
Good for you man, its a great feeling to have passed. Huge feeling of accomplishment.
I would [I]almost[/I] rather test again versus the mountain of paperwork, forms, physicals, etc. just to get the letter to test!
Congratulations on completing your 500 ton Master!!! Now get to work!
Congrats. Hope you are using it!