My repertoire

As white:

1d4 - Colle system or London system

As black:

French defence (in particular Rubinstein variation)

Nimzo and Bogo-Indian defences or Dutch Stonewall

Reverse Sicilian in the English

Stonewall or Slav against the Reti

Grunfeld set up against the Bird

Against other white openings, like b3 or b4, I just develop my pieces trying to occupy the centre.

I'm very happy with these systems, as they are not very sharp (usually) and are solid, allowing me to focus more on other aspects of the game. Also, I don't have to memorize many lines and usually I get playable positions without having to know specific lines.

What do you think?

I think you answered your own question when you said "I'm very happy with these systems". That's really all that matters.

Yes, but do you agree it is a very solid and less theoretically repertoire?

Lately, I also play the London as white and the modern as black (...g6, ...Bg7, ....an eventual ...c5).

Yes, I've played the Catalan, but it is more complicated than the Colle and London, but it is an option

I like the choices you have made as black. Never seen the Gruenfeld setup against 1.f4

Do you only play the colle and the London as white? I agree with the other poster about the Catalan. White gets a solid game, with a slight but lasting advantage. It can be complicated but so can the systems you are playing, no?

Yes, they can complicate, but comparing with other systems, they are relatively easy to play and don't require much memorization.

Note: The Grunfeld set up against the Bird is to play Nf6, g6, Bg7 and d5.