You might look at it two ways:
1) You are interested in Mastering as fast as possible, and you don't care how much money you spend, so perhaps some sort of all-in-one Mastering suite will provide some benefit with regards to time efficiency.
2) You are interested in learning about the craft of mastering, and you don't care how little money you spend, so while an all-in-one Mastering suite may provide you with an opportunity for experience, you also have the choice of learning the craft of using a wide variety of plugins, like the plugins you already own, by assembling your own chains of effects. This will give you an opportunity to enjoy a richer and deeper learning experience.
You can look at it other ways too.
I have found that, for me, using my own chains doesn't seem slow. I have found that listening to your work takes a lot more time than making a small adjustment to a parameter.
Have fun!