Reason can be used for Amatour mastering. Profeesional mastering is just very very painly in Reason.
Just try Ozone Izotope or Waves, you have very precise and powerfull tools. Reason is more like auto mastering. It sounds good and is easy for use for begginers, but it's not enough for commericial mastering.
Sorry to say that, but Reason is more like toy. You can have good effects ofc!, but it is easier, better and more precise to use proffesional mastering. If you are pro OFC. If you are begginer, it will be easier for you and you will have better effects, using Reason. If you want to go pro, better forget about Reason as a mastering device.
Thats my opinion, and friendly mastering studios, that live from mastering.
They use Waves and Izotope Ozone.