I am an extemely tight player at microstakes 6max FL. I playing only very good hands in goods spots, and folding all middle pairs and overcards. Will I be a losing player if I play too tight or am I just going to be less profitable ?

It depends on what you think your opponent(s) have. Limit holdem is a game of small edges and you will have to play as loose as possible. You can be a bit tight preflop, then try to call postflop any time possible.

Playing vs a real poker player, you will have to know exactly what hands you need to bring all the way to showdown on this or that flop vs this or that range most of the time (you need a simple and free software -- pokerstrategy web page has somewhere holdem and plo ones -- where you can input the ranges and the flops and then calculate that you need to win it at showdown e.g. 1/3rd of the time because of pot odds if you pay the turn and river bets every time), and it includes as little as ace high in many cases. The same against a bully or he also will run you over. You will play tighter vs tighter players and that already makes sure they will be losers but at weakest games, but vs you.

I have played at tight tables and they are not winning, but because of rake it is tough for me to win either, needing a longer tracking time and more experience to take still more free non game theory optimal (the software I mentioned) money where offered.

Thank you sir I will check put that software now

Yes, playing too tight can make you a losing player. However, playing too loose can also make you a losing player. Gotta find that middle ground.

In 6 max, certainly. If you are in HU pots and make folding mistakes later in hands, you're potentially spewing value.

Tight play in full ring tables is more correct, especially preflop. Even there, way too tight loses. Slowly.