If u play any one game exclusively, you might get bored (if you are one of those ppl). Besides, and this is purely from experience, tournament players are generally worse players.

If you doubt your own HU and shorthanded game this is something you absolutely myst work on! Even in FR there are lots of shorthanded situations.

Another thing you should consider is your attention span. If u cant stay focused for 6 hours, tournies are not for you untill you practice your concentration through meditation or what not.

Also, sngs require more patience than cash game. If you are the kind of person who cant fold KQ, sngs are not for you.

Poker should be something that enriches your life, and since variety is the spice of life I suggest playing all kinds of games.

You are definitely (struggling to spell that word lately) no beginner since you already grinded up your way to 50 NL. Many disagree with me on that point, but I think its vital you have great confidence in your game.

GL