Study One Opening to Play for Black or White

A friend of mine who used to teach younger students and who used to play at the 1700 level, suggested that I focus my study on the Slav defense when playing black and turn the game into the slav when playing white.

Playing white:

1.d4
2.Nf3
3.g3
4.o-o (or c3 if d4 needs support)

Playing black:

1.e4  c6
2...   d5

1.d4  d5
2...   c6

1.c4  c6
2...   d5

Do you think this is a good idea, since you only have to study lines of the Slav, or might there be a better suggestion?

One of my concerns is that while there is benefit to limiting the amount of opening theory I must study at first, I might actually prefer game play, and have more incentive to study openings, with a more open center than closed.

Your ideas?

I play a similar set up as both white and black right now, however it's because I want to avoid studying openings and focus on other chess phases right now so I just play for a safe middle game. I wouldn't advise a long term limited approach like that however because you need to expose yourself to different pawn structures and openings to see what positions excite you more and you play better with. You mentioned possibly liking open positions more, so maybe play the slav like set up as black and something else as white.

This is a fine approach for young students / new players (or so I've heard). It's not really a semi-slav because you're playing it as a system. It's like a colle as white and what I've heard called the triangle defense as black. You have fairly normal development then try for e4 (as white) or e5 (as black).

Umm, except no g3, the bishop goes to d3 as white. Not sure what to call a system with d4 and g3. I guess it would be like a schlechter slav or a catalan if the opponent cooperates.

Thanks for all your input.
I'll have to take another look at it.